我国古代对龋的认识 - shandong...
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http://1.51.214.13 Department Of Oral Pathology, Shandong University 1
我国古代对龋的认识
http://1.51.214.13 Department Of Oral Pathology, Shandong University 2
我国古代对龋的认识
http://1.51.214.13 Department Of Oral Pathology, Shandong University 3
1676年Leeuwenhoek用自制高倍显微镜,发
现龋蚀过程与微生物有关。
1867年Leber & Rotenstein在龋损中找到细
菌,并提出龋病是由产酸细菌的活动及它们
产生的酸所引起。
http://1.51.214.13 Department Of Oral Pathology, Shandong University 4
Chemico-bacterial theory
Proteolytic theory
Proteolytic-chelation theory
Three primary factors theory
http://1.51.214.13 Department Of Oral Pathology, Shandong University
化学细菌学说(chemico-bacterial theory)
化学寄生学说(chemico-parasitic theory)
酸原学说(acidogenic theory)
1889-1890年 Willoughby Dayton Miller 提出
主要内容:
① 微生物产酸
② 牙面碳水化合物是细菌代谢的主要底物
③ 酸使釉质溶解破坏 5
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④ 釉质破坏后, 牙本质无机物脱矿, 有机物分解
⑤ 龋损过程有多种混合菌参与
⑥ 龋病过程分两个阶段:酸脱矿; 酶分解基质
适宜的温度、湿度、时间
脱矿、有机物分解 细菌+糖 酸 +牙齿 龋
无机物脱矿在先,有机质破坏在后。
中心思想:
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总结了龋病过程的三项主要因素:
产酸和蛋白溶解酶的细菌;
细菌代谢所必需的碳水化合物;
发生龋的牙齿。
奠定了现代龋病病因学基础。
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该学说不能解释龋病的特异性部位;
不能解释龋为何能从平滑面开始;
未能提出牙菌斑附着和局部细菌活性概念;
未能指出特异的致龋菌群;
不能解释为什么某些人是无龋的;
不能解释静止龋现象。
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蛋白溶解学说(proteolytic theory)
1947年Gottlieb等基于早期组织学观察
提出的
有机质溶解在先,无机物脱矿在后
一些实验证实该学说的局限性
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蛋白溶解—螯合学说 (proteolytic-chelation theory)
1955年Schatz、Martin等提出
有机质和无机物同步破坏
可在碱性环境中进行
在龋病形成过程中的作用可能很小
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“三联因素”学说 (three primary factors theory)
其基本论点是:龋是由细菌(菌斑)、
食物(糖)和宿主(牙)三个主要因素相互作
用产生的,即精制的食物或(和)蔗糖进入口
腔后,经过细菌作用产生酸,酸在牙抗龋力降
低时,可使牙脱矿而形成龋,从而形成了龋的
病因学现代理论的基本要素。
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菌斑(细菌)
宿主(牙) 食物(糖)
龋病发生的“三联因素”学说
无龋
无龋 无龋
龋
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Ⅰ. Bacteria and Bacterial Plaque (细菌与菌斑)
细菌致龋的证据:
1.未萌出牙齿不发生龋
2.无菌鼠给高糖饮食不发生龋,饲料掺菌形成实
验性龋。
3.特异性链球菌接种动物形成实验性龋
4.饲料中加入低浓度抗G+菌抗生素,可使龋得到
控制。
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菌斑(bacterial plaque)
寄生在牙齿表面稠密、呈膜状的细
菌集团,它是致病菌赖以生存和发挥
其致病作用的一个复杂的微生态环境。
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根据牙菌斑所在的部位和结构
龈上菌斑 龈下菌斑 光滑面菌斑 窝沟菌斑
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根据牙菌斑的致病作用
致龋菌斑 致牙周病菌斑
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基本结构
基底层 Basal layer
中间层 Intermedium
layer
表 层 Surface layer
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Basal layer
Intermedium layer
Surface layer
Condensed microbial
Body of the plaque
Plaque-teeth interface
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水占80%,其中50%在细胞内,30%在基质中
干燥的菌斑:蛋白质 40—50%
糖 类 13—18%
脂 肪 10—14%
无机盐 5—10%
牙菌斑内含有大量的酶:淀粉酶、溶菌酶、蔗糖酶、蛋白酶、磷酸酶、葡糖基转移酶(GTF)
牙菌斑中的糖:细胞外糖和细胞内糖
多糖主要有两种:葡聚糖(Polyglucan)
果聚糖(Polyfructan)
无机物:钙、磷、镁、氟、氨等
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Formation of acquired pellicle
Bacterial aggregation
Dental plaque mature
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窝沟内菌斑以球菌占优势,其中变形链球
菌约占21%。窝沟内还有大量酵母菌。
牙齿光滑面菌斑,以放线菌的数量最多
(34.9%),球菌少些(22.9%,其中变形链球菌
仅2%左右),韦永氏球菌属13.1%,类杆菌8%。
菌斑内的细菌,常因菌斑所在的部位不同有很大差异。
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在牙菌斑内的细菌活动中,各种细菌之间存在着共生和拮抗现象。
放线菌和变形链球菌、变形链球菌和白色念珠菌之间有共生现象。
涎链球菌、干酪乳杆菌与变形链球菌之间有拮抗现象。
菌斑中致龋菌从来不占绝对优势,这一点值得注意。
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Carbohydrates
糖 丙酮酸盐
H2O + CO2 + 能量
有机酸+能量 (乳酸、甲酸、乙酸、丙酸
丁酸、戊酸、)
有氧
缺氧或无氧
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Carbohydrates
Sucrose
Sucrose Fructosyltransferase
Glucosyltransferase Polyglucan
Polyfructan
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碱性物质代谢
CO(NH2)2 NH3+CO2
COO-
+H3N C H
R
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牙菌斑内的钙磷代谢 菌斑pH值降低时
Ca10(PO4)6(OH)2+8H+ 6CaHPO4+2H2O+4Ca++
CaHPO4+ H+ CaH2PO4
菌斑pH值升高时
10CaHPO4+ 8OH-
Ca10(PO4)6(OH)2+ 4HPO4=+6HO2
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牙菌斑内其他代谢
Polyglucan Glucose 葡聚糖酶
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根据现代龋病发病的学说,多数人认为
由于酸破坏牙齿组织所致。但菌斑pH下降到
5以下时,就会发生牙齿组织脱矿,牙釉质内
的钙(羟磷灰石)被溶解。但是,菌斑内的pH
高于5时,也有可能发生钙的损失,不过量很
少而已。
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Saliva Plaque Enamel
Bacteria
Ca10(PO4)6(OH)2
Ca10(PO4)6F2
Ca2+
PO43
F ̄
Acid
Neutral
Ca10(PO4)6(OH)2
Ca10(PO4)6F2
Critical pH 5.5
Ca2+
PO43
F ̄
Buffers
Ca2+
PO43
F ̄
Ca2+
PO43
F ̄
Sucrose
Ionic exchanges at the saliva-plaque-enamel interface
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变形链球菌(S. Mutans)
血链球菌(S. Sanguis)
米勒链球菌(S. Milleri)
唾液链球菌(S. Salivarius)
轻链球菌(S. Mitis)
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链球菌属(Streptococci)
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干酪乳杆菌(L. Casei)
嗜酸乳杆菌(L. Acidophilus)
发酵乳杆菌(L. Fermentus)
链球菌属(Streptococci)
乳杆菌(Lectobacilli)
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链球菌属(Streptococci)
乳杆菌(Lectobacilli)
放线菌属(Actinomyces)
粘放线菌(A. Viscosus)
纳氏放线菌(A. Neaslundii)
溶牙质放线菌(A. Odontolyticus)
埃氏放线菌(A. Ericksonii)
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Rapid generation of acid from sucrose
Synthesis of extracellular polysaccharides
Adhesion to tooth
Increase in plaque bulk
Synthesis of intracellular polysaccharides
Acid production when sucrose absent from diet
Present in high numbers in plaque associated with
developing lesions
High numbers at particular tooth site predispose to
subsequent caries
Highly cariogenic in animal models of experimental caries
Immunization aganst S. mutans reduces caries incidence
in animal models
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Ⅱ. Substrate (食物因素)
Physical factors
Chemical Composition
Trace Element
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粗糙或纤维性
加工精细而粘性
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Carbohydrates sucrose The more sucrose intake, the higher caries incidence
sucrose>glucose>maltose,lactose,fructose>sorbitol>xylitol
Time and methods of sugar intake
Protein
Fats
Phosphates, Fluoride
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Ⅲ. Host & Teeth (宿主(牙)因素)
● The tooth factors
● Saliva factors
● Systemic fact
● Hereditary fact
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1. The tooth factors
Composition of tooth
Morphologic characteristics
Arrangement and position
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2. Saliva factors
Flow rate
Viscosity
Buffering Capcity
Calcium and phosphate ions
Antimicrobil angents
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3. Systemic factors
4. Hereditary factors
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Plaque microorganism
Susceptible Tooth
surface
Time
Substrate
龋病发生的“四联因素”学说
No
caries
No
caries
No
caries
No
caries
Caries