中药五倍子防龋的动物实验研究

目的研究五倍子在动物口腔内对变链菌生长及龋病发生、发展的影响。方法给大鼠感染致龋菌,并饲以致龋饲料2000#,分别用五倍子浸剂、氟化钠水溶液、蒸馏水给3组大鼠施药,用唾液取样细菌培养及Keyes龋齿评分法观察五倍子对变链菌在大鼠口内生长繁殖以及对龋齿发生发展的影响。结果变链菌计数五倍子组少于蒸馏水组（P<0.01）,与氟化钠组间无显著差异（P>0.05）。Keyes记分结果,五倍子组E级龋损和Ds级龋损均低于蒸馏水组（P<0.01）,与氟化钠组无差异(P>0.05)。Dm级龋损仅见于蒸馏水组。结论五倍子可以抑制大鼠口腔变链菌的生长和龋病发生、发展,其效果与氟化钠相当,有可能成为一种新型的防龋药物。     

美兰防龋的动物实验研究

目的动物实验观察美兰预防龋齿的效果,为美兰预防龋齿的临床研究提供实验依据.方法采用Keyes龋齿评分法观察美兰对Spraague-Dawley 大鼠磨牙龋的预防效果.结果在E级龋损和Ds级龋损级别中,美兰组与蒸馏水组比较相差非常显著(P<0.01),与氟化钠组相差不显著(P>0.05);Dm级龋损仅见于蒸馏水组,美兰组及氟化钠组均未发生;Dx级龋损在三组中均未出现.结论美兰能够减少Spraague-Dawley 大鼠磨牙龋的发生.     

橙皮苷防龋作用的动物实验研究

目的：研究橙皮苷在大鼠体内的防龋作用。方法：纸片扩散法检测橙皮苷对远缘链球菌（S．sobrinus）的最小抑菌浓度（MIC）,接种S．sobrinus建立大鼠龋病模型,分别用1／2 MIC橙皮苷、0．12％洗必泰、无菌蒸馏水处理大鼠口腔,菌落计数法动态监测S．sobrinus水平、Keyes龋齿评分法、激光龋齿诊断仪（DIAGNOdent）探测荧光值评价不同处理方法对大鼠龋病发生的影响。结果：橙皮苷的MIC为8 mg／ml;S．sobrinus水平：橙皮苷组与蒸馏水组相比差异无统计学意义（P＞0．05）;Keyes记分：橙皮苷组光滑面及窝沟E级龋损记分低于蒸馏水组（P＜0．05）,橙皮苷组窝沟Ds级、Dm级龋损记分低于蒸馏水组（P＜0．05）,高于洗必泰组（P＜0．05）;DIAGNOdent探测荧光值：橙皮苷组龋损程度低于蒸馏水组（P＜0．05）,高于洗必泰组（P＞0．05）。结论：1／2 MIC橙皮苷在不影响大鼠口内菌群水平的前提下,可减少大鼠磨牙龋病形成及减轻龋损程度。     

不同电动牙刷对邻面菌斑生物膜的影响

目的研究体外模型中不同运动模式和不同频率的电动牙刷对邻面菌斑生物膜的影响。 方法培养变异链球菌（S.mutans）、血链球菌（S.sanguis）和内氏放线菌（A.naeslundii）形成三菌种生物膜。实验分为4组,其中3组分别用高频率声波型电动牙刷、振动旋转型电动牙刷和低频率声波型电动牙刷在体外模型中对邻面生物膜进行非接触去除,另1组为对照组,不处理。结晶紫吸附实验半定量计算各组邻面生物膜去除量,激光共聚焦扫描显微镜观察菌斑生物膜,Comstat 2.1软件测量生物膜的总生物量、平均厚度、平均扩散距离。单因素方差分析及LSD-t检验对数据统计分析。 结果结晶紫吸附实验结果显示,高频率声波型组的生物膜去除量（0.40 ± 0.08）大于振动旋转型组的生物膜去除量（0.24 ± 0.09）,差异有统计学意义（t= 4.289,P<0.001）,同时也大于低频率声波型组的生物膜去除量（0.24 ± 0.05）,差异有统计学意义（t= 4.407,P<0.001）。高频率声波型电动牙刷组的生物膜总生物量[（7.54 ± 1.35）μm³/μm²]小于振动旋转型电动牙刷组[（11.86 ± 1.56）μm³/μm²]和低频率声波型电动牙刷组[（11.84 ± 1.42）μm³/μm²],差异有统计学意义（t_{振动旋转型组}=3.373,P_{振动旋转型组}=0.005;t_{低频率声波型组}= 3.215,P_{低频率声波型组}= 0.007）。高频率声波型电动牙刷组的生物膜平均扩散距离[（0.23 ± 0.02）μm]小于振动旋转型电动牙刷组[（0.76 ± 0.10）μm]和低频率声波型电动牙刷组[（0.71 ± 0.13）μm],差异有统计学意义（t_{振动旋转型组}=2.852,P_{振动旋转型组}= 0.014;t_{低频率声波型组}=2.470,P_{低频率声波型组}= 0.028）。 结论在体外模型中,相比振动旋转型电动牙刷和低频率声波型电动牙刷,高频率声波型电动牙刷可更高效去除邻面菌斑生物膜,降低生物膜密度。     

雷帕霉素通过促进细胞自噬抑制大鼠血管平滑肌细胞增殖活性效应

目的探讨雷帕霉素（RAP）抑制表现异常增殖活性的大鼠血管平滑肌细胞（VSMC）增殖活性的作用及其分子机制。 方法使用不同质量浓度的血小板衍生生长因子（PDGF）作为诱导剂处理大鼠主动脉VSMC，构建模拟脉管畸形的体外模型。实验分为对照组、PDGF组、PDGF+RAP组和PDGF+VEC（血管内皮细胞）组，观察对VSMC增殖活性的改变，检测不同处理方式对VSMC自噬水平的影响。两组间比较应用独立样本t检验，多组间比较应用重复测量方差分析，多组mRNA表达量、蛋白表达量比较应用单因素方差分析。 结果细胞增殖检测（CCK-8）和EdU实验结果显示：PDGF处理的VSMC活性呈时间依赖性上升。与PDGF组相比，在48和72 h，PDGF+RAP组细胞增殖活性分别降低了24.8%（0.129 ± 0.010比0.172 ± 0.012，t = 4.787，P = 0.009）和45.1%（0.170 ± 0.012比0.292 ± 0.046，t = 4.431，P = 0.011）；PDGF+VEC组细胞增殖活性分别降低了10.0%（0.155 ± 0.013比0.172 ± 0.012，t = 2.357，P = 0.076）和8.9%（0.266 ± 0.022比0.292 ± 0.046，t = 1.718，P = 0.161）。实时荧光定量PCR和蛋白免疫印迹（Western blot）结果显示，与对照组比较，PDGF可抑制平滑肌蛋白抗体-B（Smoothelin-B）表达（0.486 ± 0.057比1.005 ± 0.067，t = 10.192，P = 0.001），促进细胞视黄醇结合蛋白-1（CRBP-1）表达（3.185 ± 0.091比0.991 ± 0.056，t = 35.461，P<0.001）；而在PDGF+RAP组和PDGF+VEC组，Smoothelin-B表达增加（0.857 ± 0.091比0.486 ± 0.057，t = 5.943，P = 0.004；0.563 ± 0.067比0.486 ± 0.057，t = 1.501，P = 0.208），CRBP-1表达减少（1.579 ± 0.042比3.185 ± 0.091，t = 27.707，P<0.001；2.951 ± 0.144比3.185 ± 0.091，t = 2.382，P = 0.076）。与对照组比较，PDGF组LC3B（LC3-Ⅱ/Ⅰ比值）明显下降（0.175 ± 0.003比1.020 ± 0.020，t = 72.263，P<0.001），p62表达显著上升（2.632 ± 0.098比1.005 ± 0.007，t = 28.562，P = 0.001）。与PDGF组比较，PDGF+RAP组的LC3B明显升高（0.316 ± 0.037比0.175 ± 0.003，t = 6.529，P = 0.022），p62蛋白显著降低（1.396 ± 0.070比2.632 ± 0.098，t = 17.771，P<0.001）；PDGF+VEC组LC3B稍有上升（0.206 ± 0.014比0.175 ± 0.003，t = 3.687，P = 0.021），而p62蛋白表达降低（2.400 ± 0.076比2.632 ± 0.098，t = 3.220，P = 0.032）。透射电镜观察发现，PDGF+RAP组、PDGF+VEC组自噬小体较PDGF组上升。 结论高质量浓度PDGF可使VSMC增殖活性上升；雷帕霉素或VEC可通过激活自噬，抑制PI3K/AKT信号通路使细胞活性降低，并促使VSMC向收缩型转变，逆转PDGF的效应。     

市售饮料对SD大鼠龋齿记分和体质量影响的研究

目的了解市售饮料对SD大鼠牙齿的酸蚀作用以及对体重的影响。方法将80d龄SD大鼠36只随机分为去离子水组(A组)、雪碧组(B组)、伊利纯牛奶组(C组)、农夫山泉矿泉水组(D组)、统一鲜橙多组(E组)和康师傅鲜c组(F组),每组6只,先喂食致龋饲料1周,再各自喂食饮料3个月,每天每组喂食250ml。于实验开始和结束时测定体重,Keyes法评估鼠磨牙的患龋情况。结果伊利牛奶组龋齿记分以E级为主;农夫山泉矿泉水和去离子水两组龋齿记分仅有E级和Ds级,多为Ds级;雪碧组可达Dm级,但主要为Ds级;康师傅鲜c组及统一鲜橙多组两组的Dm和Dx记分较高,以康师傅鲜c组突出。实验前各组大鼠体质量无统计学差异,实验后伊利纯牛奶组体质量达(466.67±25.82)g,体质量增加明显,统一鲜橙多组及康师傅鲜c组次之分别为(418.33±28.58)g和(380.00±44.72)g,再次为雪碧组(356.00±37.82)g,农夫山泉矿泉水组增长最少,仅为(330.00±27.39)g。结论橙汁类饮料对牙的危害最严重,碳酸类次之,矿泉水和去离子水较弱,牛奶对牙釉质的危害最小,酸性饮料对牙齿的危害远大于牛奶和水;饮用牛奶组大鼠体质量增长明显,饮用酸性饮料的大鼠体质量增长高于饮用矿泉水和去离子水组,牛奶和酸性饮料可明显增加大鼠体质量。     

不同浓度单宁酸在不同酸蚀模式下对通用型粘接剂粘接强度的影响

目的研究不同浓度单宁酸在全酸蚀与自酸蚀条件对通用型粘接剂在牙本质表面粘接强度的影响。 方法将60颗无龋离体人磨牙置于存储盒中随机盲取分成2组（全酸蚀A组与自酸蚀B组,n = 30）,再将每组随机分为5个亚组（n = 6）。在使用通用型粘接剂Single Bond Universal（SBU）前,在牙本质面分别涂抹浓度为0%（对照组）、25%、50%、75%和100%的单宁酸3 min并冲洗吹干。实验试件在37 ℃水中保存24 h后进行微拉伸强度测试（μTBSt）。使用Two-Way ANOVA与Games-Howell对数据进行统计学分析。用体式显微镜观察断裂面模式并在扫描电镜（SEM）下观察微拉伸试件的牙本质断端。 结果在全酸蚀模式下,75%单宁酸组粘接强度[（34.51 ± 8.43）MPa]与100%单宁酸组粘接强度[（36.16 ± 5.20）MPa]显著高于其他各组（F = 32.301,P<0.001）;在自酸蚀模式下,25%单宁酸[（31.06 ± 3.41）MPa]可显著提升SBU与牙本质粘接强度（F = 23.570,P<0.001）。双因素分析结果证实,单宁酸浓度（F = 23.134,P<0.001）与酸蚀模式（F = 4.465,P = 0.036）对粘接强度具有显著影响且两要素间显著相关（F = 28.231,P<0.001）。断裂模式分析与电镜观察结果表明,在牙本质表面不同酸蚀模式与不同浓度单宁酸所形成的界面形态差异显著。 结论在不同酸蚀模式下,不同浓度的单宁酸均可显著改善SBU与牙本质的粘接强度。     

树脂浸润对人工龋表面硬度及变异链球菌生物膜形成的影响

目的研究树脂浸润技术对人工龋模型表面显微硬度（SMH）的影响及对变异链球菌生物膜的作用。 方法收集因正畸需要拔除的无龋坏前磨牙,制取釉质块共17个,其中5个用于研究树脂浸润治疗对人工龋模型SMH的影响,每个牙块分别于脱矿前（0 h）、脱矿24 h后、树脂浸润治疗后等不同时间点测量得到3组数据,自身前后对比。余下12个用于研究树脂浸润治疗对人工龋模型表面变异链球菌生物膜生长的影响,其中6个为空白对照组、6个为树脂浸润处理组,分别在4、24 h观测菌斑生物膜情况。以维氏表面微硬度仪检测人工龋模型SMH,以激光共聚焦扫描显微镜检测人工龋模型表面菌斑生物膜生物量、厚度、活菌百分比等。数据分别以配对t检验和独立样本t检验进行统计分析。 结果脱矿前釉质面SMH值为（316.07 ± 13.54）HV,脱矿24 h后为（22.44 ± 1.73）HV,树脂浸润治疗后为（139.45 ± 21.46）HV,两两比较差异有统计学意义（脱矿前-脱矿后t= 55.879,P<0.001;脱矿后-治疗后t=-14.400,P<0.001;脱矿前-治疗后t = 14.090,P<0.001）。变异链球菌生物膜检测中,4及24 h树脂浸润处理组生物量[（0.59 ± 0.24）、（9.53 ± 1.49）μm³/μm²]均低于空白对照组的生物量[（1.01 ± 0.30）、（15.47 ± 7.32）μm³/μm²],差异有统计学意义（t_{4 h}= 3.232,P_{4 h}= 0.005;t_{24 h}= 2.384,P_{24 h}= 0.042）;4及24 h树脂浸润处理组活菌百分比[（48.73 ± 8.54）%、（60.49 ± 5.33）%]均高于空白对照组的活菌百分比[（31.84 ± 7.30）%、（34.87 ± 10.72）%],差异有统计学意义（t_{4 h}=-4.508,P_{4 h}<0.001;t_{24 h}=-6.419,P_{24 h}<0.001）。树脂浸润处理组24 h生物膜厚度为（6.44 ± 1.51）μm,低于空白对照组的生物膜厚度（12.78 ± 7.17）μm,差异有统计学意义（t= 2.592,P= 0.030）。 结论树脂浸润治疗应用于早期人工龋模型上,能明显改善脱矿牙面的SMH,具有良好的机械性能;同时具有抑制变异链球菌生物膜形成的作用。     

两种材料在拔牙后引导骨组织再生位点保存术中的应用效果

目的探讨富血小板纤维蛋白（PRF）与口腔胶原膜应用于拔牙后引导骨组织再生（GBR）位点保存术中的效果。 方法从2016年6月至2018年9月期间收治的拔牙后GBR位点保存患者中选取84例进行研究，采用随机数字表法分组，观察组与对照组各42例，两组微创拔牙后均植入Bio-Oss骨替代材料，观察组表面覆盖PRF膜，对照组表面覆盖口腔胶原膜（海奥），对两组创面愈合率、牙槽骨宽度及高度、美学评分进行观察，采用独立样本t检验进行比较。 结果观察组术后2周创面愈合率为（77.1 ± 6.1）%，与同期对照组（65.8 ± 3.7）%对比，差异有统计学意义（t = 10.188，P<0.001）；观察组术后4周创面愈合率为（98.8 ± 12.5）%，与同期对照组（78.7 ± 7.1）%对比，差异有统计学意义（t = 9.084，P<0.001）。拔牙前，两组牙槽骨高度差异无统计学意义（t = 0.022，P = 0.982）；拔牙后1个月，观察组牙槽骨高度为（15.1 ± 1.9）mm，与同期对照组（14.2 ± 1.8）mm对比，差异有统计学意义（t = 2.091，P = 0.039）；拔牙后3个月，观察组牙槽骨高度为（14.2 ± 1.8）mm，与同期对照组（14.0 ± 1.3）mm，差异有统计学意义（t = 2.608，P = 0.010）。拔牙前，两组牙槽骨宽度差异无统计学意义（t=0.062，P=0.950）；拔牙后1个月，观察组牙槽骨宽度为（7.1 ± 0.6）mm，与同期对照组（6.8 ± 0.7）mm对比，差异有统计学意义（t=2.392，P=0.019）；拔牙后3个月，观察组牙槽骨宽度为（6.9 ± 0.4）mm，与同期对照组（6.4 ± 0.5）mm对比，差异有统计学意义（t = 5.748，P<0.001）。修复后即刻，两组PES评分差异无统计学意义（t = 0.142，P = 0.887）；修复后3个月，观察组PES评分为（12.4 ± 4.0）分，与同期对照组（10.5 ± 2.0）分对比，差异有统计学意义（t = 2.644，P = 0.009）；修复后6个月，两组PES评分差异无统计学意义（t = 0.617，P = 0.538）。修复后即刻，两组WES评分差异无统计学意义（t = 0.261，P = 0.794）；修复后3个月，观察组WES评分为（9.1 ± 1.0）分，与同期对照组（8.1 ± 0.7）分对比，差异有统计学意义（t = 5.176，P<0.001）；修复后6个月，两组WES差异无统计学意义（t = 1.318，P = 0.191）。 结论PRF用于拔牙后GBR位点保存术中的效果优于口腔胶原膜，可提高创面愈合率，也能保持牙槽骨宽度与高度，取得满意的短期美学效果，更值得推广。     

牙髓干细胞对牙周炎中破骨细胞的作用

目的研究牙髓干细胞（DPSC）对牙周炎中破骨细胞形成及牙槽骨再生的影响,并初步探索DPSC对小鼠破骨细胞的作用机制。 方法体外诱导小鼠骨髓单核细胞破骨分化,观察破骨细胞组（OC组）及其与DPSC共培养组（OC+DPSC组）的抗酒石酸酸性磷酸酶（TRAP）染色情况,实时荧光定量聚合酶链反应（PCR）检测破骨分化相关基因包括活化T细胞核因子（NFATc1）、基质金属蛋白酶9（MMP-9）及TRAP的表达差异。体内构建小鼠慢性牙周炎模型,通过微计算机体层摄影（micro-CT）扫描后三维重建,比较慢性牙周炎+0.9%氯化钠溶液注射组（NS组）和慢性牙周炎+DPSC注射组（DPSC组）釉牙骨质界至牙槽嵴顶（CEJ-ABC）距离,并对标本进行苏木精-伊红和TRAP染色,观察DPSC对小鼠破骨细胞及牙槽骨再生的影响。采用SPSS 20.0软件进行数据统计分析,采用独立样本t检验及校正t检验分析组间差异。 结果体外TRAP染色发现,与DPSC共培养明显抑制成熟破骨细胞形成,OC+DPSC组成熟破骨细胞均数（4.2 ± 0.2）少于OC组均数（6.8 ± 0.2）,差异有统计学意义（t= 15.922,P<0.001）;破骨细胞表面积均数（0.046 ± 0.007）mm²也明显小于OC组（0.763 ± 0.015）mm²,差异有统计学意义（t = 83.174,P<0.001）。相对OC组,OC+DPSC共培养组的MMP-9、NFATc1及TRAP的mRNA相对表达量明显降低,均值分别为0.38 ± 0.17（t = 6.217,P = 0.003）、0.24 ± 0.12（t = 10.569,P = 0.003）和0.55 ± 0.13（t = 6.077,P = 0.026）。micro-CT扫描结果显示,DPSC注射组CEJ-ABC的平均距离为（0.215 ± 0.017）mm,明显小于0.9%氯化钠溶液组（0.311 ± 0.022）mm,差异有统计学意义（t= 10.921,P<0.001）,组织学观察下DPSC组炎症反应较0.9%氯化钠溶液组轻,且破骨细胞更少。 结论DPSC可通过抑制牙周炎破骨细胞的形成从而促进牙槽骨再生,有望作为一种可局部注射的骨代谢双向调节生物制剂,治疗临床上包括牙周炎等因骨代谢失衡引起的炎症性骨吸收疾病。     

Microbiology of root surface caries in humans

Studies on the microbiology of root surface caries between 1970 and 1975 placed emphasis on Gram-positive pleomorphic filamentous rods, particularly Actinomyces viscosus and Actinomyces naeslundii. Both of these species had been shown to produce root surface caries in experimental animals. Since this time, studies have placed more emphasis on Streptococcus mutans, and S. mutans and Lactobacillus are significant in prediction of root surface caries risk in patients. Subsequent studies confirmed an association between S. mutans and 'soft' or 'initial' root lesions. Thus, it is important when determining the microflora of root surface lesions to make careful characterization of the state of the lesion. A second important aspect of the analysis of bacterial communities associated with root surface caries is better definition of the organisms. Most studies have concentrated on 'target organisms' S. mutans, S. sanguis, A. viscosus, A. naeslundii, Lactobacillus, and Veillonella. However, it has been known for 17 years that the Actinomyces associated with the lesions may be variants of A. viscosus and A. naeslundii. Such strains (intermediate strains) have been described in taxonomic studies of Actinomyces, yet little is known of the differences in physiology of these strains or their relationship to root surface caries. A similar situation exists with oral Streptococcus where new taxonomic divisions are being proposed. Recognition of the potential diversity within the 'target' genera of root surface caries could yield valuable data. Recent studies suggest that this is so, since samples from root surface lesions which contain S. mutans and Lactobacillus show a high isolation of S. mitis 1 and no isolations of A. naeslundii. Careful definition of the lesions of root surface caries and the flora will allow analysis to relate a specific bacterial community to the state fo the lesion and assist in monitoring the control of the lesion through fluoride and antibacterials.     

纳米无机载银磷酸锆树脂基托对6种口腔细菌的体外抗菌研究

目的:通过体外粘附实验,研究纳米无机载银磷酸锆加入到树脂基托中后是否具有抗菌性。方法:将纳米无机载银磷酸锆(Conval PAg-40型)按1%、3%、5%、7%比例添加到树脂基托中制成树脂片,未添加者为对照组,打磨抛光,金相显微镜观察试件表面无划痕、粗糙度测定仪测得表面粗糙度值无统计学差异后,采用薄膜密贴法检测该抗菌树脂片对变形链球菌、黏性放线菌、内氏放线菌、血链球菌、牙龈卟啉单胞菌、白色念珠菌的抗菌性,比较分析树脂基托抗菌性能与添加抗菌剂比例的相关性。结果:3%、5%、7%组培养的牙龈卟啉单胞菌以及1%、3%、5%、7%组培养的变形链球菌、黏性放线菌、内氏放线菌、血链球菌、白色念珠菌菌落数均低于对照组,差异有统计学意义(P<0.05),抗菌率随添加比例的增加逐渐升高;1%组培养的牙龈卟啉单胞菌菌落数与对照组相比差异无统计学意义(P>0.05)。结论:纳米无机载银磷酸锆树脂基托有良好的抗菌效能,其抗菌率随抗菌剂比例的添加而呈线性上升趋势。     

伊犁黑蜂蜂胶对口腔主要致龋细菌生物膜作用的实验研究

目的 研究伊犁黑蜂蜂胶对口腔常见致龋细菌生物膜的影响,探讨其防龋效果及可能的防龋机制。方法 通过结晶紫染色法测定黑蜂蜂胶对口腔常见致龋菌（变异链球菌、表兄链球菌、血链球菌、黏性放线菌、内氏放线菌）的最小生物膜清除浓度（MBEC）;培养测试细菌24 h单菌生物膜,加入MBEC及以下的3个浓度配置成初始pH值为7.0的含药培养基,厌氧培养24 h后测pH值,并计算pH变化值以检测不同浓度黑蜂蜂胶对测试菌单菌生物膜产酸能力的影响。蒽酮法测定MBEC及以下的3个浓度的黑蜂蜂胶对变异链球菌24 h单菌生物膜产生水不溶性胞外多糖的影响。结果 黑蜂蜂胶对变异链球菌、表兄链球菌、血链球菌、黏性放线菌、内氏放线菌的MBEC分别是6.25、1.56、3.13、0.78、0.78 mg•mL-1;黑蜂蜂胶可使各测试菌单菌生物膜ΔpH降低,蜂胶各组与对照组相比差异均有统计学意义（P<0.05）;在MBEC浓度时,蜂胶可使变异链球菌合成水不溶性胞外多糖的能力降低。结论 伊犁黑蜂蜂胶具有一定的防龋效果,其可能的防龋机制是通过有效清除口腔主要致龋细菌单菌生物膜,抑制测试菌株产酸、合成水不溶性胞外多糖的能力起作用的。     

The predominant microflora of nursing caries lesions.

The predominant microflora recovered from infected dentine of 52 carious teeth from 14 children with nursing caries was determined using both selective and non-selective media for the isolation of specific genera and acidified media (pH 5.2) to isolate the predominant aciduric microorganisms, and compared with the microflora of sound enamel surfaces in caries-free children. Streptococcus mutans formed a significantly greater proportion of the lesion flora while Streptococcus oralis, Streptococcus sanguis and Streptococcus gordonii formed a significantly greater proportion of the plaque flora from sound tooth surfaces. The proportions of Actinomyces naeslundii and Actinomyces odontolyticus were significantly greater in the plaque samples than in the lesion samples. Actinomyces israelii formed 18.2% of the flora from the lesions, but was not isolated from the plaque samples. The proportions of Candida albicans, Lactobacillus spp. and Veillonella spp. were also significantly greater in the carious dentine than in the plaque samples. The most frequently isolated lactobacilli were Lactobacillus casei, Lactobacillus fermentum and Lactobacillus rhamnosus. The predominant aciduric flora was S. oralis, S. mutans and A. israelii and these taxa were also isolated from a similar proportion of the lesions at pH 7.0. Strains of S. mutans, L. casei, L. fermentum and L. rhamnosus isolated from individual carious teeth were genotyped using PCR-based methods. Each species was genotypically heterogeneous and different genotypes were recovered from different carious teeth in the same child. These data indicate that the microflora of lesions in the same child is microbiologically diverse and support a non-specific aetiology for nursing caries in which the physiological characteristics of the infecting flora, not its composition, is the major determinant underlying the disease process.     

The association of selected bacteria with the lesions of root surface caries

Plaque from the root surfaces of 165 subjects (mean age 65.5 years, 22-26 teeth/subject) was analysed for specific bacteria. Five subject groups were defined: A (DMFS 16.4), B (DMFS 55.9), C1 (DMFS 55.6), C2 (DMFS 57.0) and C3 (DMFS 48.1). Groups C1 and C2 had unrestored root surface lesions; Group A, B and C3 were free of unrestored root caries and differed in their coronal caries experience. Streptococcus mutans was isolated more frequently from the root lesions in Groups C1 and C2 than from intact root surfaces in Group A. Streptococcus oralis, Streptococcus mitis 1 and Streptococcus sanguis were isolated more frequently from Group A. The percentage contribution that S. mutans made to plaque from lesions in Groups C1 and C2 was higher than that from plaque in Group A and Actinomyces viscosus serovar 2 contributed more to plaque in Group C1 than in samples from Group A. The percentage counts of Lactobacillus in plaque from lesions in Groups C1 and C2 were higher than those from intact roots in Groups A, B, and C3. Subjects were also grouped on the presence of Lactobacillus and S. mutans in plaque samples. Samples with both organisms (n = 17) showed significantly higher isolation frequencies of specific strains of S. mitis 1 and also A. viscosus serovar 2 compared with samples of plaque containing S. mutans or Lactobacillus. Actinomyces naeslundii serovar 1 was not isolated from samples containing both S. mutans and Lactobacillus. The results confirm an association of S. mutans and Lactobacillus with root surface lesions and suggest a relationship between lesions and A. viscosus serovar 2.     

Effects of highly concentrated stannous fluoride and chlorhexidine regimes on human dental plaque flora

The aim of this study was to determine the effect of an intensive antimicrobial treatment on the number of Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus/Actinomyces naeslundii, and the total Colony-forming Units (CFU) in plaque. The dentition of human volunteers was treated in a dental office with either chlorhexidine (5%) or stannous fluoride (8%). Following the office treatment with chlorhexidine, selected volunteers rinsed daily at home for seven or 49 days with chlorhexidine solution (0.2%), while another group flossed daily at home for seven days with dental floss impregnated with chlorhexidine. On days one, seven, 21, 35, and 49 after the local applications, we took saliva samples and plaque samples from fissures, smooth surfaces, and approximal areas. Chlorhexidine and stannous fluoride suppressed S. mutans and the Actinomyces species on all surfaces and in saliva. S. mutans on tooth surfaces was suppressed for approximately seven days and returned to the baseline level at day 21. A. viscosus/naeslundii was suppressed for more than seven days on the teeth. S. sanguis and the total CFU returned to the baseline level within seven days on all surfaces and in saliva. Rinsing or flossing with chlorhexidine suppressed S. mutans during the period of time that these supplements were used. Brushing for seven days with chlorhexidine gel (1%) without a preceding intensive chlorhexidine treatment had virtually no effect on S. mutans in approximal areas and in saliva, but suppressed S. mutans in fissures and on smooth surfaces.     

Interbacterial aggregation of actinomyces naeslundii and dental plaque streptococci

The ability of human Actinomyces naeslundii strains to aggregate with dental plaque streptococci was found to be strain specific. A. naeslundii strains aggregated strongly more often with specific strains of Streptococcus sanguis and Streptococcus mitis than with Streptococcus mutans strains. The effects of proteolytic enzymes and heat on the interbacterial affinities of A. naeslundii 398A and S. sanguis S, two strains which were found to aggregate strongly, were studied. Enzyme or heat treatment of 398 A, but not S. sanguis S, impaired aggregation. Electron microscopic examination of aggregates of untreated bacteria revealed that the attachment between cells of strains 398 A and S was mediated by short tufts of electron-dense fuzzy components of the cell surfaces. The affinity between cells of A. naeslundii and the streptococci which readily colonize cleaned smooth tooth surfaces may account, in part, for the previously-reported, delayed increase in A. naeslundii proportions among bacteria forming early plaque deposits.     

人工合成抗菌肽对口腔细菌抗菌性能的初步研究

目的 评价人工合成抗菌肽（十肽）对口腔常见感染性疾病主要致病菌的抑菌活性。方法 采用琼脂扩散法及液体稀释法体外评价十肽对变异链球菌、表兄链球菌、嗜酸乳杆菌、血链球菌、格氏链球菌、黏性放线菌、内氏放线菌、牙龈卟啉单胞菌、中间普雷沃菌、具核梭杆菌、伴放线嗜血杆菌及白色假丝酵母菌的抑菌性能,并测定十肽对变异链球菌的时间-杀菌曲线。结果 十肽对所选实验菌株均表现出不同的抑菌性能,对主要致龋菌的最小抑菌浓度MIC值为62.5~125 μg·mL^-1,而对主要牙周致病菌的MIC值为250~1 000 μg·mL^-1,其中,十肽对龋病主要致病菌变异链球菌有较强抑菌作用。时间-杀菌曲线结果显示,十肽作用20 min后开始杀菌,30 min之后可完全杀灭细菌,且在24 h之内无细菌生长。结论 新型人工合成抗菌肽十肽对口腔常见感染性疾病主要致病菌具有抑菌性能,其中对致龋变异链球菌的抑菌效果最为明显。     

Microbial flora associated with presence of root surface caries in periodontally treated patients

Abstract — Examination of saliva and dental plaque was carried out in 35 adults who had been treated for periodontal disease 3 yr earlier. Plaque samples were collected from approximal and buccal sound and carious root surfaces. The samples were analyzed for the presence and proportions of members of Streptococcus, Lactobacillus and Actinomyces. The results showed a low prevalence of root surface caries and a low level of salivary mutans streptococci and lactobacilli. From subjects with root caries there was a not statistically significant tendency to higher proportional levels of mutans streptococci in plaque from carious root surfaces than from caries-free surfaces. An inverse significant relationship between noncarious and carious root surfaces was noted for S. sanguis. The population of A. viscosus and A. naeslundii was similar in plaque samples from sound and carious sites but showed elevated levels in the subjects with five or more new root surface lesions.     

The association of bacterial adhesion with dental caries.

Saliva adhesion of bacteria is a key event in oral biofilm formation. Here, we used partial least-squares (PLS) analysis to correlate adhesion of cariogenic (Streptococcus mutans Ingbritt) and commensal (Actinomyces naeslundii LY7) model bacteria, and their agglutinin and acidic proline-rich protein ligands, respectively, with high and low caries experiences in 38 children reflecting today's skewed caries distribution. Adhesion of S. mutans was among the factors correlating strongest with high caries experience when PLS modeled together with traditional factors (e.g., sugar intake, lactobacilli counts). Saliva phenotypes with high agglutinin levels and Db-s (an acidic PRP variant) coincided with both high caries experience and S. mutans adhesion. A. naeslundii adhesion correlated with low caries experience. Non-Db phenotypes (i.e., acidic PRP-1 and PRP-2 variants) coincided with both low caries experience and S. mutans, but high A. naeslundii, adhesion. Thus, bacterial adhesion may modulate susceptibility and resistance to dental caries.