Microsoft PowerPoint - 09 tooth shedding2(更).ppt [相容模式]

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口腔胚胎及組織學 Oral embryology & histology Shedding and Eruption of tooth 學習目標能了解頭臉部及口腔之發育結構與功能, 並發展能有效吸收與傳播相關資訊之辭彙, 將胚胎及組織學上之基本概念, 應用於臨床上之診斷與治療臺北醫學大學牙醫學系鄧乃嘉醫師 dianaten@tmu.edu.tw 參考資料 1.

Esstential of Oral Histology and Embryology--A clinical approach: James K Avery, Denial J Chiego,Jr 3rd Edition, Elsevier Mosby, 2006 3.

1 口腔胚胎及組織學 Oral embryology & histology Shedding and Eruption of tooth 學習目標能了解頭臉部及口腔之發育結構與功能, 並發展能有效吸收與傳播相關資訊之辭彙, 將胚胎及組織學上之基本概念, 應用於臨床上之診斷與治療臺北醫學大學牙醫學系鄧乃嘉醫師參考資料 1.Illustrated Dental Embryology, Histology, and Anatomy: Mary Bath-Balogh, Margaret J. Fehrenbach, 2nd Edition, Elsevier Saunders, Esstential of Oral Histology and Embryology--A clinical approach: James K Avery, Denial J Chiego,Jr 3rd Edition, Elsevier Mosby, Ten Cate's Oral Histology: Development, Structure, and Function: Nanci Anatonio, 6th ed. Mosby, 2003 Summary 提供學生探討頭臉部及口腔之發育, 認識牙齒及口腔組織之正常顯微結構, 並了解其功能與結構之關係, 進而對生理病理與臨床牙科學上之問題能做比較與思考, 為各牙科臨床科目之重要基礎課程 Mixed dentition of a 7-year-old child Teeth vary in size, shape and their location in the jaws. These differences enable teeth to work together to help you chew, speak and smile. They also help give your face its shape and form. At birth people usually have 20 primary (baby) teeth, which often erupt as early as six months of age. They are then shed at various times throughout childhood. By age 21, all 32 of the permanent teeth have usually erupted. 1

Tooth eruption is defined as The movement of a tooth from its site of development within the alveolar process to its functional position in oral cavity, Massier and Schour, 1941 Tooth Movement

Eruptive tooth movement: tooth move from its position within the bone to its functional position in occlusion.

EXFOLIATION When primary teeth get ready to fall out and make way for the eruption of permanent teeth, they go through a process called exfoliation (shedding).

The premature loss of primary teeth can have a serious impact on the eruption of permanent teeth and how they will be in position in the dental arch.

2 Tooth eruption is defined as The movement of a tooth from its site of development within the alveolar process to its functional position in oral cavity, Massier and Schour, 1941 Tooth Movement Preeruptive tooth movement: Deciduous and permanent tooth germs within tissues of the jaw before they begin to erupt. Eruptive tooth movement: tooth move from its position within the bone to its functional position in occlusion.(intraosseous & extraosseous) Posteruptive tooth movement: maintaining the position of the erupted tooth in occlusion, compensate for jaw growth, occlusal & proximal tooth wear. EXFOLIATION When primary teeth get ready to fall out and make way for the eruption of permanent teeth, they go through a process called exfoliation (shedding). The root of the primary tooth resorbs (looses structure) as the permanent tooth erupts from beneath. The primary teeth act as guides for the developing permanent teeth. The premature loss of primary teeth can have a serious impact on the eruption of permanent teeth and how they will be in position in the dental arch. Preerupted tooth (deciduous) movement Preerupted tooth (permanent) movement 1. A lengthening of the jaw 2. Deciduous 2nd molar tooth germ move backward. 3. Anterior tooth germ move forward 4. Tooth germ move outward & upward. 5. Jaw bone increase the length, width & height. Length of jaw Tooth germs develop on the lingual aspect of their deciduous predecessors, in the same bony crypt. Incisor and Canine are on the lingual side of the root. Premolar tooth germs are positioned between the divergent roots of the deciduous molar. Width of jaw 2

Preerupted tooth (permanent) movement Permanent tooth germs

of Shedding - Gubernacular Canal - Osteoclasts - Odontoclasts

features: Gubernacular cord: The fibrocellular follicle

the lamina propria of the oral mucous membrane by means of a

lamina Gubernacular canal: Holes, once contained the

The canal is filled with connective tissue that connects the

3 Preerupted tooth (permanent) movement Permanent tooth germs without predecessors: Upper jaw: facing distally and swing into position. Lower jaw: Mesial inclination then becomes vertical Histology of Shedding - Gubernacular Canal - Osteoclasts - Odontoclasts - Periodontal Ligament Eruptive tooth movement Histological features: Gubernacular cord: The fibrocellular follicle surrounding a seccessional tooth retainds its connection with the lamina propria of the oral mucous membrane by means of a strand of fibrous tissue containing remnants of the dental lamina Gubernacular canal: Holes, once contained the Gubernacular cord. The canal is filled with connective tissue that connects the dental follicle to the oral epithelium. 牙齒在牙冠形成後朝口腔方向的移位被稱為是兒童成長發育的一種現象, 它的機轉以往被認為有 : 1) 牙根的形成 2) 牙周韌帶膠原纖維的變化 3) 齒槽骨的生長 4) 引牙萌發索 (gubernacular cord) 的收縮 5) 牙髓血管壓力 6) 造纖維細胞 (fibroblast) 的收縮 3

在 1961 年 Gowgiel 及 1980 年 Carl 等的研究發現無根牙仍然會萌發, 證明了與牙根的形成無關 1971 年 Berkovitz 發現齧齒類動物門齒的萌發需要完整的牙周韌帶, 提示了牙齒萌發時牙周韌帶的重要性但是在 1972~1973 年 Matena 發表了齧齒類動物門齒與人類有不同機轉的報告之後, 有關牙齒萌發的研究即改用狗做實驗 Cahill 等在 1982

(dental follicle) 用外科手術取出後牙齒就無法萌發, 而且在不傷及齒濾泡的情況下把牙齒從骨內取出再將另一物體埋入齒濾泡後此物體便會萌發, 給了我們牙齒萌發需要有齒濾泡的存在的重要觀念因此, 許多細胞學方面的研究將重點放在齒濾泡與骨吸收之間的關係, 而這些研究結果讓我們更近一步了解了牙齒萌發的機轉 ; 當牙齒正要萌發時牙冠外圍的齒濾泡內會出現很多單核細胞 (mononuclear

4 在 1961 年 Gowgiel 及 1980 年 Carl 等的研究發現無根牙仍然會萌發, 證明了與牙根的形成無關 1971 年 Berkovitz 發現齧齒類動物門齒的萌發需要完整的牙周韌帶, 提示了牙齒萌發時牙周韌帶的重要性但是在 1972~1973 年 Matena 發表了齧齒類動物門齒與人類有不同機轉的報告之後, 有關牙齒萌發的研究即改用狗做實驗 Cahill 等在 1982 年用狗做的實驗發現了牙周韌帶沒有與骨隱窩 (bony crypt) 接觸的牙齒仍然會萌發, 推翻了 Berkovitz 的理論 Cahill 用狗做的一連串的實驗發現骨內的牙齒用鋼絲固定後雖然會失去萌發的動作, 然而牙齒上方的齒槽骨仍然會吸收形成一個萌發路徑, 當被固定的牙齒被鬆解後便快速萌發, 同時牙齒下方會出現骨小樑, 顯示了在牙齒萌發過程中骨吸收與骨添加的重要性發現將齒濾泡 (dental follicle) 用外科手術取出後牙齒就無法萌發, 而且在不傷及齒濾泡的情況下把牙齒從骨內取出再將另一物體埋入齒濾泡後此物體便會萌發, 給了我們牙齒萌發需要有齒濾泡的存在的重要觀念因此, 許多細胞學方面的研究將重點放在齒濾泡與骨吸收之間的關係, 而這些研究結果讓我們更近一步了解了牙齒萌發的機轉 ; 當牙齒正要萌發時牙冠外圍的齒濾泡內會出現很多單核細胞 (mononuclear cell), 這些單核細胞進入齒濾泡外圍的骨隱窩後彼此結合形成破骨細胞 (osteoclast), 隨著破骨細胞的增加齒濾泡內的單核細胞的數目便會減少 CSF-1(Colony stimulating factor-1) 及 EGF (epidermal growth factor) 與牙齒萌發機轉有關關於 CSF-1 的報告提示了單核細胞的分化成熟需要有 CSF-1 的存在, 有些報告提到注射 CSF-1 會使齒濾泡內的單核細胞顯著增加且同時也會促使骨隱窩裡的破骨細胞數目增加而導致牙齒萌發的速度加速關於 EGF 的研究結果發現 EGF 會促進牙乳頭 (dental papilla) 及牙釉器官 (enamel organ) 產生 IL-1 α(interleukin- α) 及 TGF-β1 (transforming growth factor-β1) 而增加 CSF-1 的形成, 因此注射 EGF 同樣會促進 signaling molecules CSF-1 EGF IL-1 TGF alpha TGF beta-1 Mechanism of Eruptive tooth movement Root Formation Bone remodeling Dental follicle Periodontal ligament Molecular determinants of tooth eruption 4

Accommodation for growth (14~18ys) Compensation

tissue pressures) (However, Dental Follicle

Potential) Pattern of Shedding Pattern of shedding

5 Conclusion of FORCES of Tooth Eruption Multifactorial Posteruptive tooth movement Accommodation for growth (14~18ys) Compensation for occlusal wear (PDL & cementum) Accommodation for interproximal i wear (mesial drift: contraction of the transseptal ligament and soft tissue pressures) (However, Dental Follicle Activity & Bone Remodeling have the Highest Potential) Pattern of Shedding Pattern of shedding Resorption of roots anterior/posteriori / i Shedding of crown Pattern of shedding Shedding of teeth 5

Shedding of teeth Cause of shedding Pressure from permanent teeth loss of bone weakening of supporter trauma

Odotoclast The resorption of hard tissue is achieved by cells with a histological nature similar to that of

Odontoclasts derive from the monocyte and migrate from blood vessels to the resorption site, where they fuse

Odotoclast Ultrastructure of odontoclasts and their precusor. A.

Mononuclear precursor cell attached to the predentin surface C. Mutinucleate odontoclast resorbing predentin.

from the dentin surface, and the remaining pulp cells now deposit a cementlike tissue on it.

6 Shedding of teeth Cause of shedding Pressure from permanent teeth loss of bone weakening of supporter trauma and inflammation occlusal stress, caries.. Etc. Odotoclast The resorption of hard tissue is achieved by cells with a histological nature similar to that of osteoclasts, but because of their involvement in the removal of dental tissue, they are called odontoclasts. Odontoclasts derive from the monocyte and migrate from blood vessels to the resorption site, where they fuse to form the characteristic multinucleated odontoclast with a clear attachment zone and ruffled border. Odotoclast Ultrastructure of odontoclasts and their precusor. A. Mononuclear precursor cell in the pulp chamber B. Mononuclear precursor cell attached to the predentin surface C. Mutinucleate odontoclast resorbing predentin. D. Multinucleate odontoclast resorbing dentin Odotoclast Resorption ceases as the Odontoclasts migrate away from the dentin surface, and the remaining pulp cells now deposit a cementlike tissue on it. The tooth then sheds, with some pulpal tissue intact. Resorption of soft tissue Loss of PDL fibers is abrupt. A PDL fibroblast in an area preceding the root resorption front. Its cytoplasm is filled with collagen, suggesting an interference with the protein synthetic and/or degradative cell physiology. 6

Pressure Abnormal tooth movement Pressure from the

Growth of the face and jaws and the corresponding

mastication probably increase the forces applied to

of the tooth is damaged and tooth resorption is

movement Tooth drifts mesially by combined actions of

with it TOOTH MOVEMENT Tooth drifts mesially by

Osteoblasts laying down bundle bone Earlier bone

7 Pressure Abnormal tooth movement Pressure from the eruption successional tooth plays a role in shedding. Growth of the face and jaws and the corresponding enlargement in size and strength of the muscles of mastication probably increase the forces applied to the deciduous teeth so that the supporting apparatus of the tooth is damaged and tooth resorption is initiated Abnormal tooth movement Orthodontic tooth movement Tooth drifts mesially by combined actions of osteoclasts & osteoblasts moving bone, taking tooth with it TOOTH MOVEMENT Tooth drifts mesially by combined actions of osteoclasts & osteoblasts moving bone, taking tooth with it TOOTH MOVEMENT Osteoblasts laying down bundle bone Earlier bone position Osteoclasts resorbing bone Basil Basil 7

8 Eruption & shedding THANKS 8

Microsoft PowerPoint - 13 Mucosa(更).ppt [相容模式]

Microsoft PowerPoint - 13 Mucosa(更).ppt [相容模式] 口腔胚胎及組織學 Oral embryology & histology Mucosa 臺北醫學大學牙醫學系張維仁醫師 cweijen1@tmu.edu.tw 學習目標能了解頭臉部及口腔之發育結構與功能, 並發展能有效吸收與傳播相關資訊之辭彙, 將胚胎及組織學上之基本概念, 應用於臨床上之診斷與治療參考資料 1.Illustrated Dental Embryology, Histology,