4种义齿基托材料表面润湿性的实验研究

目的 评价临床常用的钴铬合金、钴铬钼合金、纯钛和热凝型义齿基托树脂的润湿性,为临床选择合适的全口义齿基托材料提供理论指导。 方法 分别测定人工唾液在不同处理的钴铬合金、钴铬钼合金、纯钛、热凝型义齿基托树脂上的接触角,通过接触角大小反应4种材料的润湿性。 结果 按临床实际磨光处理组别的接触角均比磨光成镜面状组的小,且差异具有统计学意义。磨光成镜面状组别中热凝型义齿基托树脂接触角最大,其次是纯钛,钴铬合金和钴铬钼合金接触角最小,除钴铬合金和钴铬钼合金外其余材料两两间比较差异均具有统计学意义。按临床实际磨光处理组中接触角最大的是纯钛,其次为热凝型义齿基托树脂,钴铬合金和钴铬钼合金接触角最小,除钴铬合金和钴铬钼合金外其余材料两两间比较差异均具有统计学意义。结论 钴铬合金和钴铬钼合金润湿性优于纯钛和热凝型义齿基托树脂,从润湿性对固位力的影响角度考虑,选择这两种材料制作全口义齿基托对全口义齿的固位更加有利。     

上颌钛制腭托全口义齿临床应用的回顾性研究

目的：探讨纯钛作为全口义齿上颌腭托材料在口腔内长期应用后的临床效果。方法：选择由同一全口义齿专家多次镶配全口义齿的患者11例，最后一副义齿为钛制上颌腭托，进行满意度问卷调查及义齿检查。结果：采用传统PMMA制作的全口义齿的重做原因，主要是上颌基托折裂(72．7％)，其次为不舒适(27．3％)和固位差(27．3％)，改用钛制腭托义齿后，平均戴用2．95年未出现折裂；72．8％的患者认为钛制腭托义齿优于PMMA腭托义齿，主要表现在异物感小，固位好，舒适，质轻，可以改善口干症状，18．2％的患者认为两种义齿使用效果不存在明显差别。钛制义齿磨光面45．4％出现色素沉着，27．2％颜色变暗。腭部粘膜未见明显炎症。在咀嚼功能、发苦、冷热刺激的敏感性及味觉方面两种材料义齿没有明显差别。结论：全口义齿上颌腭托采用纯钛制作，其抗折性能、舒适性优于传统PMMA，但长期应用后，部分腭托磨光面出现色素沉着及颜色变暗，对固位及适合性的影响因受个人因素、义齿制作质量的影响，有待进一步研究。     

纯钛表面聚吡咯涂层的表面性能研究

目的：纯钛表面电化学聚合聚吡咯涂层并研究其表面性能。方法：采用恒电流法以0.25mA/cm^3、1mA/cm^2、4mA/cm^2的电流密度制备两种支撑电解质Cl^-和ToS^-的纯钛表面聚吡咯涂层。利用SEM、表面粗糙度仪以及接触角测量仪检测涂层表面性能。结果：随聚合电流密度增大，表面粗糙度（Ra、Rz值）和表面接触角逐渐增大，而表面自由能逐渐减小。在相同的聚合密度电流下，ToS^-搀杂组的表面粗糙度（Ra、Rz值）、表面接触角均大于Cl^-搀杂组；而表面自由能则小于Cl^-搀杂组。结论：聚吡咯的表面性质，如表面形貌、润湿性、表面自由能，可以通过改变搀杂离子种类和聚合电流密度来进行调整。     

氟对纯钛表面变形链球菌和血链球菌黏附的影响

目的研究氟对纯钛表面变形链球菌和血链球菌黏附的影响。方法采用四唑盐比色法检测经不同浓度氟化钠人工唾液浸泡24 h后变形链球菌和血链球菌在纯钛表面的黏附情况,并用原子力显微镜分析变形链球菌和血链球菌黏附后纯钛表面的粗糙度及表面形貌。采用SPSS 11.0软件包对数据进行统计学分析。结果经不同浓度氟化钠人工唾液浸泡后,变形链球菌和血链球菌在纯钛表面黏附的OD值随着氟化钠浓度的升高越来越大：0 g/L < 0.5 g/L < 1.0 g/L < 2.0g/L (P<0.05)。此外,变形链球菌和血链球菌黏附后,纯钛表面的粗糙度Ra值随着氟化钠浓度的升高也越来越大：0 g/L < 0.5 g/L < 1.0 g/L < 2.0g/L (P<0.05);纯钛的表面形貌有明显差异,无论是经变形链球菌还是经血链球菌黏附后,随着氟化钠浓度的升高,纯钛表面均变得越来越粗糙、不平整。结论经不同浓度氟化钠人工唾液浸泡后,变形链球菌和血链球菌在纯钛表面的黏附、黏附后粗糙度及表面形貌结果一致,提示氟化钠加剧了纯钛的腐蚀,使得纯钛表面的粗糙度增加,进而促进了变形链球菌和血链球菌在纯钛表面的黏附。     

义齿自动研磨机的研制

目的 :设计并开发一种适用于义齿研磨、抛光的自动研磨机 ,以代替传统的手工方法。方法 :将两个六角形的研磨桶对称地连于圆形底盘上 ,通过自转和公转运动 ,利用离心力使研磨桶中的义齿与磨料和研磨液相互摩擦 ,达到研磨、抛光目的。结果 :采用不同转速和磨料 ,利用义齿自动研磨机对纯钛义齿部件进行自动研磨 ,使纯钛部件的表面粗糙度Ra值从 1.0 60 μm降至 0 .3 113 μm ,达到临床标准。 结论 :使用义齿自动研磨机对义齿金属部件的研磨效果可以达到临床要求     

钛制腭托全口义齿的临床应用

目的：观察钛制腭托全口义齿临床应用效果。方法：对100例无牙殆患者采用二次印模法,取功能性印模,常规制作钛腭托全口义齿,并进行1～3年的临床疗效观察。结果：临床应用观察得知,钛制腭托全口义齿固位好,异物感小,基托轻薄,没有金属味,抗折力强。尤其以前曾戴用过PMMA全口义齿的患者更换钛制腭托全口义齿后感觉更舒适,适应期明显缩短。其满意度达85％。其中3例患有轻度口腔干燥症的患者对钛制基托全口义齿满意度明显高于PMMA全口义齿,钛制腭托在3年的使用过程中尚未发现基托折裂现象。但是有40％的患者钛腭托磨光面使用后出现色素沉着,这可能与患者的饮食习惯和口腔卫生以及义齿加工质量有关。     

等离子渗氮后纯钛的耐磨性能的研究

目的:模拟口腔环境,研究在牙刷磨耗机的磨擦下,等离子渗氮对纯钛的耐磨性能的影响。方法:铸造纯钛试件24片,随机分为0.2%NaF渗氮组、0.2%NaF未渗氮组、人工唾液渗氮组、人工唾液未渗氮组,在牙刷磨耗机上刷洗75 000次,对比刷洗前后的粗糙度Ra增加值及色彩变化,并在扫描电镜下观察试件表面形貌。结果:与未渗氮组比较,0.2%NaF等离子渗氮后纯钛的表面粗糙度Ra增加值及色彩变化差异均有显著性(P<0.05);不同混合液比较,0.2%NaF溶液对试件的耐磨性能影响较人工唾液的影响大(P<0.05)。SEM观察表明:在0.2%NaF溶液中刷洗后未渗氮组纯钛试件表面磨耗现象严重。结论:等离子渗氮后纯钛的耐磨性能得到提高;含氟溶液能降低纯钛表面的耐磨性能。     

3种义齿基托材料抛光后表面粗糙度的比较研究

目的研究3种义齿基托材料抛光前后的表面粗糙度度。方法选择聚甲基丙烯酸基托树脂（PMMA）、弹性义齿材料和不碎胶等3种义齿基托材料,将材料制成12mm×12mm×2mm的标准试件,每种材料各20个,对试件进行打磨和抛光后,采用表面轮廓测量仪检测材料抛光前后的表面粗糙度,通过扫描电镜对材料表面形貌进行表面观察。结果PMMA、弹性义齿材料和不碎胶抛光后表面粗糙度分别为（0．160±0．018）μm、（0．110±0．011）μm和（0．141±0．017）μ。弹性义齿材料和不碎胶的表面粗糙度低于PMMA（P〈0．05）,表面划痕也少于PMMA。结论弹性义齿材料和不碎胶更能获得抛光效果,表面粗糙度优于PMMA。     

真空电弧离子镀对纯钛表面粗糙度影响的研究

目的:评价电弧离子镀膜对纯钛表面粗糙度的影响,为临床应用提供实验依据。方法:铸造12mm×12mm×1.4mm的纯钛试样共8个,常规喷砂和抛光处理后,分别测试真空电弧离子镀膜处理前和处理后的钛试件表面粗糙度(Ra),并进行配对T检验统计处理。结果:真空电弧离子镀膜表面处理前后表面粗糙度无统计学差异(P>0.5)。结论:电弧离子镀膜技术对铸钛件表面的粗糙度无不良影响,用于钛支架的表面着色改性,能保持原义齿表面的加工质量。     

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全口义齿是为牙列缺失患者制作的义齿,对于单颌全口义齿来说,固位和抗折裂是获得良好长期修复效果的基础。由于对牙合余留牙的存在,单颌全口义齿往往受到较大的咬合力;牙合平面曲线的不规整,并可造成较大的侧向力,时间长则易导致单颌全口义齿的松脱和折裂。近年来,我们对采用不同材料制作上颌全口义齿的患者进行回访,以观察注塑、钴铬合金、纯钛3种义齿材料用于上颌全口义齿修复的优缺点。     

Effect of enzymatic and NaOCl treatments on acrylic roughness and on biofilm accumulation

As denture cleansers should be able to reduce biofilm accumulation without changing the acrylic resin surface structure, this study evaluated the effect of denture cleansers on surface roughness of acrylic resin and on biofilm accumulation. It was conducted a crossover study of three phases of 4 days each and 13 volunteers wore palatal appliances containing four specimens of acrylic resin of known surface roughness which were extra-orally submitted once a day to three groups of separated treatments: (i) negative control, (ii) enzymatic commercial solution (Ortoform) or (iii) 0.5% sodium hypochlorite (NaOCl).The appliances were immersed eight times a day in a 20% sucrose solution to enhance biofilm formation. On morning of the fifth day of each phase, the amount of biofilm formed on the specimens was estimated by the amount of protein extracted with alkali and the surface roughness of the specimens was again measured. New palatal appliances with new specimens were worn by the volunteers in the following phases, but the treatments were changed. The roughness of the resin increased after the treatments (P < 0.05) but the difference among the cleansers was not statistically significant (P = 0.85). The lowest amount of biofilm formed on acrylic resin specimens was found for the treatment with NaOCl (P < 0.05) but the enzymatic product did not differ from the negative control group (P > 0.05). The data suggest that the roughness of acrylic resin was not changed by the cleansers, but the ability to reduce biofilm accumulation depended on the product used.     

Effects of fluoride and methanehydroxydiphosphate on enamel and on dentine demineralization.

The aim of this article was to investigate the effects of methanehydroxydiphosphonate (MHDP) and fluoride (F) separately and combined, on the demineralization process in enamel and in dentine under constant composition conditions. The demineralization was carried out in solutions containing 3 mM calcium, 3 mM phosphate, pH = 5.0, and either 6 microM MHDP, 12 microM F or 6 microM MHDP and 12 microM F. After demineralization periods (t) between 24 and 140 h, the lesion depth l and the mineral loss delta Z were measured by transverse microradiography of the enamel and dentine specimens. The amount of mineral lost during demineralization averaged over the lesion depth, R = delta Z/l, was calculated. R approximately 17 vol% for both enamel and dentine, both delta Z and l being greater for dentine than for enamel by approximately the same factor. The results show that under the same conditions dentine is attacked much more strongly than enamel. The lesion progress with time is quite different for the two tissues: in enamel the lesion depth progresses als l3 = alpha t + beta, in dentine as l2 = alpha't + beta'. The slopes alpha and alpha' decrease in the order MHDP > F > MHDP+F. In enamel the combined inhibitor effect is only slightly larger than the effect of F alone; in dentine the inhibiting effects of F and MHDP are approximately additive. The inhibitor interactions can be described by the Langmuir adsorption theory.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of mAs and kVp on resolution and on image contrast.

Two clinical experiments were conducted to study the effect of kVp and mAs on resolution and on image contrast percentage. The resolution was measured with a "test pattern." By using a transmission densitometer, image contrast percentage was determined by a mathematical formula. In the first part of the experiment, the density of the film was kept constant by changing the kVp and mAs. In the second part of the experiment, different mAs's were chosen, and for each mAs, several kVp's were used. Five observers read the radiographs. The first experiment showed that, when the film density is kept constant, the higher the kVp, the lower the resolution and image contrast percentage; also, the higher the mAs, the higher the resolution and image contrast percentage. The second experiment showed that when the film density is not kept constant, the correlation between kVp and resolution and between kVp and image contrast percentage was the same as in the first experiment. However, there was negligible correlation between mAs and resolution and between mAs and image contrast percentage. A high positive correlation was found between resolution and image contrast percentage, but a high negative correlation was found between resolution and film density.     

Effect of chlorhexidine and toothbrushing on the presence of bacteria on gingival and buccal epithelial cells

Swabs of buccal and gingival epithelial cells from healthy young adult donors were washed in physiological saline solution, smeared on glass slides and stained with acridine orange. The presence of bacteria attached onto epithelial cells was examined under a fluorescence microscope. Four hours after a chlorhexidine rinse, the number of cells with > 50 attached bacteria had almost completely vanished. The degree of bacterial colonization seemed to re-establish at a level exceeding the baseline. One week after chlorhexidine treatment the degree of colonization was still over the control level. Toothbrushing with a conventional toothpaste reduced immediately the number of cells with > 50 bacteria. The colonization had re-established to the pre-washing levels at the buccal sites at 1 h and at the gingival sites at 4 h after toothbrushing. A method for the evaluating of the antimicrobial power of oral hygiene products is presented.     

Effects of diabetes mellitus on periodontal and peri-implant conditions: update on associations and risks

Objectives: To review the evidence for the association between diabetes and periodontal and peri-implant conditions and the impact of periodontal therapy in subjects with diabetes.
Material and Methods: A search of MEDLINE-PubMed was performed up to and including December 2007. The search was limited to clinical studies published in English. Publications on animal studies were excluded. The selection criteria included all levels of available evidence.
Results: Evidence on the association between diabetes and periodontitis supports the concept of increased severity but not extent of periodontitis in subjects with poorly controlled diabetes. Subjects with controlled diabetes do not show an increase in extent and severity of periodontitis. Periodontitis is associated with poor glycaemic control and diabetes-related complications. It is inconclusive that periodontal therapy with or without the use of antibiotics results in improvements of glycaemic control and of markers of systemic inflammation. Evidence is lacking to indicate that implant therapy in subjects with diabetes yields long-term outcomes comparable with those of non-diabetic subjects.
Conclusions: Poorly controlled diabetes may be considered a risk factor for increased severity of periodontitis. The effects of periodontal therapy on glycaemic control and systemic inflammation is not proven beyond doubt and need to be confirmed in large-scale randomized-controlled clinical trials.     

Effect of starch and sucrose on dental biofilm formation and on root dentine demineralization

The cariogenicity of starch alone or in combination with sucrose is controversial and the effect on dentine demineralization and on the dental biofilm formed has not been explored under controlled conditions. A crossover, single-blind study was conducted in four steps of 14 days each, during which 11 volunteers wore palatal appliance containing 10 slabs of root dentine to which the following treatments were applied extraorally: 2% starch gel-like solution (starch group); 10% sucrose solution (sucrose group); a solution containing 2% starch and 10% sucrose (starch + sucrose group), or 2% starch solution followed by 10% sucrose solution (starch --> sucrose group). On the 14th day of each phase the biofilms were collected for biochemical and microbiological analyses, and dentine demineralization was assessed by hardness. A higher demineralization was found in dentine exposed to sucrose and starch sucrose combinations than to starch alone (p < 0.01), but the sucrose-containing groups did not differ significantly from each other (p > 0.05). The concentrations of soluble and insoluble extracellular polysaccharides (EPS), and the proportion of insoluble EPS, were lower in the biofilm formed in presence of starch (p < 0.01) than in those formed in the presence of sucrose or sucrose/starch combinations; however, no significant difference was observed among the groups containing sucrose (p > 0.05). RNA was successfully isolated and purified from in situ biofilms and only biofilms formed in response to sucrose and starch/sucrose combinations showed detectable levels of gtfB and gtfC mRNA. The findings suggest that the combination of starch with sucrose may not be more cariogenic to dentine than sucrose alone.     

Effects of sugared and sugar-free chewing gum on the accumulation of plaque and debris on the teeth

Abstract The aim of this study was to determine the effects of sugar-free and sugar-containing gums on plaque formation, established plaque and salivary debris. Plaque accumulating during three 5-day periods was recorded in a group of 10 students who, in the absence of normal oral hygiene methods, chewed sugar-free or sugar-containing chewing gum or did not chew gum. In a second group of 10 students the effect of chewing the two types of gum on 3-day accumulations of plaque was recorded. Finally, the wet weight of liquorice debris present in saliva with and without gum chewing, was recorded. During the no chewing periods distinct and significant differences in the amounts of plaque accumulating at different sites were apparent. Both types of chewing gum significantly and comparably reduced plaque accumulation during the 5-day period. The chewing gums also significantly reduced established plaque on many tooth surfaces. Salivary debris was significantly reduced by 50% after chewing gum. It was noted that plaque removal occurred primarily from sites remote from the gingival margin and interdental areas and therefore it was concluded that the observed effects of chewing gum on plaque would not be reflected in a reduction in gingival inflammation.     

Effects of fluoride- and chlorhexidine-containing varnishes on plaque composition and on demineralization of dentinal grooves in situ

The aim of the study was to compare the effects of Cervitec, containing 1% chlorhexidine (CHX) and 1% thymol, Fluor Protector, containing 0.1% fluoride, their 1:1 mixture, and a placebo varnish on the percentage of mutans streptococci and lactobacilli in plaque and on the underlying dentin demineralization, as assessed by microradiography. Bovine dentine discs, fitted with three parallel grooves, received one of the varnish treatments into the first groove and on the adjacent part of the dentin surface. Volunteers (n = 23) wore the discs fixed to their partial dentures for four consecutive 3 wk periods. Microbiological analysis of plaque accumulated in the grooves showed no difference between groups. Fluoride varnishes (Fluor Protector and mixed varnish) had a significantly larger inhibitory effect on mineral loss in the treated groove than Cervitec or placebo. All treatment varnishes had more pronounced effect in panelists (n = 14) with higher degree of demineralization (mineral loss in placebo group > or = 1,200 vol% x microm). In these panelists, CHX-containing varnishes showed an inhibitory effect on demineralization in all grooves, also in the two non-varnished grooves. As fluoride varnishes had the largest localized effect on demineralization, and CHX varnishes were showing a peripheral effect, a combined treatment could be the preferred method to obtain an optimal caries preventive effect in caries-prone individuals.     

全瓷高嵌体修复前磨牙缺损的近、远期效果及对牙功能的影响

目的: 探讨全瓷高嵌体修复前磨牙缺损的近、远期疗效及对牙功能的影响。方法: 选择北京大学人民医院2017年1月—2018年1月收治的95颗经根管治疗后的前磨牙,随机分为对照组（n=47）和实验组（n=48）。对照组采用全冠修复,实验组采用全瓷高嵌体修复。比较2组患牙成功、存留、失败情况,比较修复体6、12、36个月美国公众健康服务标准（USPHS）评估情况及牙咬合功能。采用SPSS 19.0软件包对数据进行统计学分析。结果: 实验组患牙修复成功率、存活率高于对照组,但差异无统计学意义（P>0.05）;12个月时,2组修复体外形、边缘密合性、边缘着色、表面质地、继发龋、牙龈健康、邻接关系相比,差异无统计学意义（P>0.05）;36个月时,2组修复体边缘密合性、边缘着色、表面质地相比,差异均无统计学意义（P>0.05）,实验组外形、继发龋、牙龈健康、邻接关系情况显著优于对照组（P<0.05）;6、12、36个月时,2组患者患侧咬合功能与对侧相比,差异无统计学意义（P>0.05）。结论: 全瓷高嵌体修复前磨牙缺损成功率、存留率高,近、远期修复效果好,有利于改善患牙咬合功能。     

The effect of zirconia and titanium surfaces on biofilm formation and on host-derived immunological parameters

The aim of this study was to analyse the effect of zirconia and titanium surfaces on biofilm formation and host-derived parameters. Studies comparing zirconia and titanium surfaces were selected up to September 1, 2019. The outcome measures were surface roughness, contact angle, bacterial count, bacterial adherence, biofilm thickness, bacterial distribution, and specifically investigated biofilm and specific host-derived immunological parameters. Random-effects meta-analyses of in vitro and in vivo studies were conducted. A total of 39 studies were included for data extraction. In the systematic review data, 10 studies stated that zirconia accumulated less initial oral biofilm parameters, 16 investigations showed negligible inter-material differences, and only one study showed that zirconia attracted the most biofilm. However, in the meta-analysis, the bacterial coverage was found to be significantly superior for zirconia surfaces (P <  0.00001); the other outcome measures did not show any statistically significant differences between zirconia and titanium for the remaining parameters and the studies presented a substantial degree of heterogeneity. Overall, on the basis of the meta-analysis, the current data situation does not allow a clear preference for the use of zirconia or titanium.