不同龋敏感儿童口腔变异链球菌不同基因型临床分离株产酸力的实验研究

目的比较不同龋敏感儿童口腔变异链球菌不同基因型临床分离株对蔗糖进行酵解产生有机酸的能力。方法从不同龋敏感的3~5岁学龄前儿童口腔变异链球菌中选取66株变异链球菌临床分离株,用气相色谱法测定高龋、中龋和无龋儿童口腔变异链球菌不同基因型临床分离株产生各有机酸的量。结果不同龋敏感儿童不同基因型变异链球菌临床分离株产生有机酸的量的差异有统计学意义（P<0.05）,同一龋敏感儿童变异链球菌携带不同基因型菌株产酸量的差异也有统计学意义（P<0.05）,携带基因型数目越多的菌株其产酸量越多。变异链球菌临床分离株产生乳酸、乙酸、甲酸的量的差异有统计学意义（P<0.05）,乳酸多于乙酸和甲酸。结论不同龋敏感儿童口腔变异链球菌不同基因型菌株产酸力不同,携带基因型数目越多的菌株其产酸力越强。     

不同龋敏感儿童变异链球菌临床分离株耐酸能力的实验研究

目的:比较不同龋敏感儿童口腔中变异链球菌临床分离株耐酸能力的差异。方法:以高龋、中龋和无龋儿童口腔中分离得到的变异链球菌为实验菌株,以ATCC25175国际标准株作对照,经常规复苏、增菌后,配制相同浓度的菌悬液,pH在7.0～6.0时各菌株间的耐酸能力无显著差异(P>0.05),而当pH在5.5～5.0时,分别在不同pH(以0.5为间隔,pH 4.0～7.0)的BHI液体培养基中培养48 h后,用紫外分光光度计在540 nm处测定吸光度,比较细菌的生长情况。结果:高、中龋病人口腔中分离出的变异链球菌临床分离株和国际标准菌株的耐酸能力明显高于无龋者口腔中分离出的变异链球菌,差异具有统计学意义(P<0.05)。结论:高龋儿童口腔中变异链球菌临床分离株具有高致龋性。     

猛性龋儿童变链菌分离株耐酸性实验研究

目的：确定猛性龋儿童变链菌和远缘链球菌临床株的耐酸性。方法：采用紫外分光光度计比较猛性龋、非猛性龋、无龋儿童变链菌（各6株）和远缘链球菌（猛性龋儿童6株,非猛性龋和无龋儿童各3株）临床株在体外不同初始pH条件下的生长情况。结果：初始pH4．5－5．5条件下,各组变链菌生长抑制程度均明显大于远缘链球菌（P＜0．05）。初始pH4．5条件下,猛性龋儿童远缘链球菌分离株耐酸性明显强于非猛性龋和无龋儿童分离菌株（P＜0．05）。结论：远缘链球菌的耐酸性强于变链菌;猛性龋儿童远缘链球菌分离株耐酸性强。     

猛性龋儿童变链菌分离株耐酸性实验研究

目的 :确定猛性龋儿童变链菌和远缘链球菌临床株的耐酸性。方法 :采用紫外分光光度计比较猛性龋、非猛性龋、无龋儿童变链菌 (各 6株 )和远缘链球菌 (猛性龋儿童 6株 ,非猛性龋和无龋儿童各 3株 )临床株在体外不同初始 pH条件下的生长情况。 结果 :初始 pH 4.5～ 5 .5条件下 ,各组变链菌生长抑制程度均明显大于远缘链球菌(P <0 .0 5 )。初始pH 4.5条件下 ,猛性龋儿童远缘链球菌分离株耐酸性明显强于非猛性龋和无龋儿童分离菌株(P <0 .0 5 )。结论 :远缘链球菌的耐酸性强于变链菌 ;猛性龋儿童远缘链球菌分离株耐酸性强     

变形链球菌(血清型C)临床分离株AP-PCR基因分型

目的 探讨变形链球菌（血清型C）菌珠基因型与龋发生的关系。方法 用Chelex法撮细菌染色体DNA,经多次实验自行确立AP－PCR最佳反应条件,并对278株来自不同龋敏感个体的临床分离株进行AP－PCR基因型分析。结果 278株变链菌临床分离株共区分出105种基因型,无龋个体84．21％携带1种基因型,而高龋患者95％携带2种或2种以上基因型。结论 变链菌菌株间存在明显的遗传多态性,个体携带变链球菌基因型的种数与其致龋性密切相关。     

儿童猛性龋变链菌分离株的产酸性

目的：确定儿童猛性龋变链菌和远缘链球菌临床分离株的产酸性。方法：采用酸度计和自动气相色谱仪比较儿童猛性龋、非猛性龋、无龋变链菌（各6株）和远缘链球菌（儿童猛性龋6株,非猛性龋和无龋各3株）的临床株降低环境pH值的能力（ΔpH）和乳酸产量,并以此推测其致龋力。结果：远缘链球菌ΔpH及乳酸产量均高于变链菌,特别是在低pH水平下,二者差异更为显著（P＜0．05）。儿童猛性龋远缘链球菌分离株ΔpH和乳酸产量显著大于非猛性龋和无龋分离菌株（P＜0．05）。结论：远缘链球菌的产酸能力强于变链菌;儿童猛性龋远缘链球菌分离株较非猛性龋和无龋儿童分离菌株产酸性更强。     

不同龋敏感儿童变形链球菌临床分离株产酸、耐酸能力的实验研究

目的:比较不同龋敏感儿童口腔中变形链球菌的临床分离株产酸和耐酸能力的差异.方法:以高龋、中龋和无龋儿童口腔中分离得到的变形链球菌为实验菌株,常规复苏、增菌,配制相同密度的菌悬液,加入含5%蔗糖、不同pH值(以0.5为间隔,pH 4.0～7.0)的BHI液体培养基中厌氧(80%N2、10%H,、10%CO2)培养48 h后,采用pHS-3C型精密酸度计,测定培养物上清的终末pH值,比较细菌的产酸能力(△pH);将相同菌液浓度的变形链球菌临床分离株菌悬液分别在不同pH(以0.5为间隔,pH 4.0～7.0)的BHI液体培养基中培养48 h后,用紫外分光光度计测定540 nm处吸光度,比较细菌的牛长情况.结果:儿童高、中龋患者口腔中分离出的变形链球菌临床分离株以及国际标准菌株的产酸和耐酸能力明显高于无龋者口腔中分离出的变形链球菌,差异具有统计学意义(P＜0.05).结论:高龋儿童口腔中变形链球菌临床分离株具有高致龋性.     

猛性龋儿童变链菌分离株的蔗糖粘附能力

目的探讨猛性龋儿童变链茵和远缘链球菌临床分离株的蔗糖依赖性粘附能力.方法采用紫外分光光度计,检测猛性龋、非猛性龋、无龋儿童变链茵(各6株)和远缘链球菌(猛性龋儿童6株,非猛性龋和无龋儿童各3株)临床株在含蔗糖培养液中对玻壁的粘附情况.结果各组变链茵分离株之间及各组远缘链球菌分离株之间对玻壁的粘附比无显著差异;各组远缘链球菌菌株对玻壁的粘附能力显著大于各组变链菌菌株(P＜0.05).结论猛性龋儿童变链菌和远缘链球菌临床株蔗糖依赖性粘附能力与非猛性龋及无龋儿童分离菌株无差别;远缘链球菌蔗糖依赖性粘附能力强于变链茵.     

封闭型维吾尔族和汉族不同龋敏感儿童口腔变形链球菌临床分离株LDH活性与龋病相关性研究

目的：研究新疆封闭型维吾尔族和汉族不同龋敏感儿童变形链球菌乳酸脱氢酶（LDH）活性与龋病发生的相关性。方法：对喀什市3~5岁封闭型维吾尔族儿童179名、汉族儿童289名进行口腔变形链球菌分离培养,选取119株高龋菌株[龋失补牙数（dmft）≥5],120株无龋菌株[龋失补牙数（dmft）=0],通过还原性辅酶Ⅰ氧化法测定乳酸脱氢酶活性。结果：维族儿童变链菌LDH活性均值较汉族儿童高（P=0.025）,维族儿童高龋组LDH活性均值高于汉族儿童（P=0.018）,维族儿童无龋组LDH活性均值与汉族儿童无龋组比较无显著差异（P=0.239）。两族儿童高龋组LDH活性均值均高于无龋组,差异有统计学意义（P=0.000）。总体样本中,不同LDH活性菌株分布在高龋组和无龋组差异有统计学意义（P=0.000）。维、汉族不同LDH活性菌株分布在高龋组和无龋组的差异有统计学意义（高龋组P=0.04;无龋组P=0.013）,维、汉族不同LDH活性菌株在高龋组和无龋组的分布与其活性有相关性（维吾尔族P=0.000;汉族P=0.000）。结论：不同LDH活性菌株在两组儿童分布与其LDH活性有关,变形链球菌LDH活性与乳牙龋的发生有一定的相关性。     

老年人高龋患者牙菌斑中变形链球菌临床分离株耐酸能力的研究

目的:分析老年人高龋患者牙菌斑中,变形链球菌临床分离株(血清型C)在酸性条件下生存的耐酸能力。方法:体外培养从老年人高龋患者、无龋者牙菌斑中分离的101种不同基因型变形链球菌株临床分离株(血清型C),检测菌株在不同的pH条件下的耐酸能力。结果:老年人高龋患者口腔中分离出的变形链球菌临床分离株耐酸能力明显高于无龋组,与国际参考菌株无明显的统计学差异。同时研究发现,在老年人高龋患者同一个体的口腔中,变形链球菌临床分离株耐酸能力存在明显差异。结论:老年人高龋患者牙菌斑中变形链球菌临床分离株(血清型C)的高致龋性,与其携带有耐酸能力强的菌株关系密切。     

Long-term monitoring of microleakage of different amalgams with different liners

STATEMENT OF PROBLEM: Microleakage is a major factor contributing to the occurrence of secondary caries around amalgam restorations. Purpose The purpose of this study was to evaluate the effect of amalgam type, liner type, and storage period on microleakage. MATERIAL AND METHODS: Two hundred seventy bovine incisors were divided into 18 groups (n = 15). Two high-copper amalgam alloys (admixed and spherical type) and 3 liner options (no liner, varnish, and adhesive) were used to restore Class V preparations. After placement of restorations, the teeth were stored for 3 different periods (1 day, 1 week, and 12 months) in saline solution, After storage, the specimens were immersed in 0.5% methylene blue for 24 hours, sectioned, and then mean depth of dye penetration was measured separately for the incisal and cervical areas with the use of a binocular microscope (x200). Scores were assigned to a millimeter scale (+/- 0.2 mm). The data were analyzed with a 3-way analysis of variance and the Tukey Honestly Significant Different test (alpha = .05). RESULTS: The 3-way interaction was significant (P < .001 for the cervical and occlusal margins). After short-term storage (1 day and 1 week), the admixed alloy showed significantly lower leakage values than the spherical alloy only in cervical margins (1.45 and 1.56 for the admixed and 1.62 and 1.50 for the spherical alloy at the cervical [P = .034] and incisal margins [P = .702]), respectively. After 12 months, values decreased significantly for both amalgams, which were similar and lower than for the short-term storage period (short-term values of 1.62 and 1.39 for the admixed and 1.69 and 1.46 for the spherical alloy at the cervical and incisal margins, respectively; long-term values of 0.22 and 0.20 for the admixed and 0.33 and 0.36 for the spherical alloy at the cervical and incisal margins, respectively [P < .019]). When the adhesive was used, significantly superior sealing was observed for both amalgams. For the no liner and cavity varnish groups, the admixed alloy showed superior performance compared to the spherical alloy (with no liner, 1.11 and 0.98 for the admixed and 0.83 and 1.08 for the spherical alloy at the cervical and incisal margins, respectively; with varnish, 1.19 and 1.22 for the admixed and 1.63 and 1.34 for the spherical alloy, at the cervical and incisal margins, respectively [P < .037]). CONCLUSION: In the short-term, the lowest degree of leakage was found when adhesive was used. After 1 year, no differences were detected, regardless of the amalgam type and liner used.     

The retention of complete crowns prepared with three different tapers and luted with four different cements

STATEMENT OF PROBLEM: The role of adhesive properties of cements on the retentive strength of crowns with different degrees of taper is not clear. PURPOSE: This study evaluated the retention of full crowns prepared with 3 different tapers and cemented with 2 conventional and 2 adhesive resin cements. MATERIAL AND METHODS: One hundred twenty sound human molar teeth were assigned randomly to 1 of 12 groups, (n=10). The groups represented the 4 cements: zinc phosphate (Fleck's), a conventional glass ionomer (Ketac-Cem); 2 adhesive resin cements (C&B Metabond and Panavia); and 3 tapers of 6-degrees, 12-degrees, and 24-degrees within each cement. Crowns were cast with a high noble alloy. The 6-degree taper was considered the control within each cement group. Retention was measured (MPa) by separating the metal crowns from the prepared teeth under tension on a universal testing machine. Analysis of variance was used to test the main effects on the retentive strength of full crowns, namely cements, tapers, and failure modes. The Fisher's multiple comparison test was used to evaluate the source of the differences. The chi(2) analyses were used to examine the relationships between failure types, cements, and tapers. All statistical tests were conducted at alpha=.05. RESULTS: There was a significant difference in the main effect cement (P<.0001) and taper (P=.0002). The mean retentive strength values of both Fleck's and Ketac-Cem were significantly lower than the mean retentive strength values of both C&B Metabond and Panavia (P<.0001). The retention of crowns prepared with 6-degree taper was not significant from the 12-degree taper (P=.0666). The difference in retention was significant between the 6-degree taper and the 24-degree taper (P<.0001) and between 12-degree taper and 24-degree taper (P=.0178). The types of failure were adhesive in the cement (65%), cohesive in the tooth (31%), and assembly failure (fracture of embedding resin) (4%). The type of failure was dependent on the degree of taper (P<.0001) and on the type of cement (P<.0042). CONCLUSION: Within the limitations of this study, the retentive values of the adhesive resins at 24-degree taper were 20% higher than the retentive values of the conventional cements at 6-degree taper. The use of resin luting agents yielded retention values that were double the values of zinc phosphate or conventional glass ionomer cement.     

不同正畸托槽粘接剂及釉质抛光方法对牙釉质着色的影响

目的： 比较3种不同托槽粘接剂和4种不同釉质抛光方法对牙釉质颜色改变的影响。方法： 选取120颗正畸需要拔除的前磨牙，随机分为3组，分别使用3种不同正畸托槽粘接剂-化学固化树脂粘接剂、光固化树脂粘接剂和树脂改性玻璃离子粘接剂，每组再随机抽取10颗牙分为4组，分别选择4种不同釉质抛光方法去除粘接剂并抛光牙釉质：碳化钨车针（TC）、碳化钨车针+Sof-Lex抛光杯（TC+SL）、碳化钨车针+One Gloss抛光杯（TC+OG）和碳化钨车针+PoGo抛光杯（TC+PG）。将上述抛光后的牙在咖啡溶液中放置7 d后，用Crystaleye分光光度比色仪进行釉质着色变化值测量。采用SPSS13.0软件包对数据进行双因素方差分析和Bonferroni法分析。结果： 不同抛光方法的组内差异表现为TC组釉质表面颜色变化差异最大，TC+SL组变化值最低，TC+SL和TC+PG组变化值无显著差异（P> 0.05）。不同粘接剂的组间差异表现为树脂改性玻璃离子粘接剂组样本着色变化值最低，化学固化树脂组样本着色变化值最高（P<0.05）。结论： 不同粘接剂类型和釉质抛光方法对釉质表面的着色变化有显著影响。     

不同规格分牙簧的应力分析

目的 分析不同规格分牙簧的应力，找出形状结构因素对分牙簧力学行为影响的规律。方法 对分牙簧进行一维实体网格划分并输入材料性能参数。然后按力作用点的位移不同，从小到大逐步加载，应用ANSYS分析软件计算不同型号分牙簧在不同应变量时产生的应力值。结果 分牙簧的应力大小与力臂长短有关，力臂短者产生的力值大；分牙簧的应力随位移的增加而增大，其变化规律可用公式F=A Bx表示。结论 分牙簧应力随其尺寸与力作用点位移而变化，临床医生可根据矫治需要在一定范围内选择适宜的分牙簧以调节其作用力值。     

Inflammation associated with implants with different surface types

OBJECTIVES: The aim of this study was to determine the nature of the inflammatory infiltrate associated with different transmucosal implant surfaces in dogs. METHODS: Three experimental and one control single-stage implants were randomly placed on each side of the jaw in eight dogs. The transmucosal portion of the test implants consisted of an acid-etched surface (type A), a machined surface with a circumferential groove (type C) and a surface prepared by mild anodic oxidation (type D). The control was a standard machined surface (type B). In order to determine the response to the different surfaces, plaque control was carried out twice weekly following placement of the implants for the entire period of the experiment. At 6 months, gingival biopsies and plaque samples were obtained. The area of inflammatory infiltrate and the nature of the infiltrating cell types were determined using immunohistology. Real-time polymerase chain reaction was used to identify putative periodontal pathogens. RESULTS: Inflammatory infiltrates were associated with all implant surfaces and were commonly found subepithelially and perivascularly. T cells were the predominant infiltrating cell type in all lesions, associated with the different surfaces. In all lesions the CD4 : CD8 ratio was approximately 2 : 1. Statistical analysis showed that the type C surface (machined surface with a groove) had significantly larger inflammatory infiltrates than the type B surface (machined surface without a groove; P<0.05). No statistically significant differences were found with respect to the size of the inflammatory infiltrates or in terms of the nature of infiltrating cells. However, despite the intensive plaque control regime, plaque was present on all implant surfaces at the time of biopsy 6 months after placement. All implants had similar numbers of Tannerella forsythia, Fusobacterium nucleatum and Porphyromonas gingivalis. Actinobacillus actinomycetemcomitans, was not detected in any sample. CONCLUSIONS: These results suggest that the development of inflammation associated with implants is independent of surface type, but is nevertheless associated with the presence of plaque. The different surfaces had no influence on the nature of the infiltrate, with T cells being the predominant cell type in all lesions. Finally, the different implant surface types seemed not to influence the peri-implant microbiota. However, the presence of the circumferential groove tended to be associated with larger infiltrates. Whether this is due to increased plaque accumulation remains to be determined.     

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。     

不同轴壁聚合度的金属全冠固位力的比较

目的比较3种轴壁聚合度全冠的固位力,探讨其固位效果。方法选用离体上颌前磨牙,进行4°、8°和12°的预备,翻制合金代模,制作金属全冠。比较其粘固前、后的固位力。结果粘固前,4°预备体的全冠脱位力值(177.35±17.13)N,明显大于8°组(102.95±13.66)N和12°组(51.80±9.51)N;粘固后,4°预备体的全冠脱位力值(346.60±30.93)N明显大于8°组(247.95±20.64)N和12°组(216.05±17.35)N。粘固后,4°组脱位力值提高了95.4%,8°组提高140.8%,12°组提高317.1%。结论轴壁聚合度越大,全冠固位力越小。粘固后,轴壁聚合度越大,固位力增幅越大。