牙齿健康部位与龋损部位菌斑pH变化的比较研究

目的研究进食糖后患龋情况不同者健康牙面或龋洞内菌斑pH的变化规律,为进一步探明龋病的发病机制提供依据.方法采用接触法直接在原位测定菌斑pH在漱糖后1 h内的变化.实验分3组,分别为无龋组(CF)、普通龋组(CIA)和龋活跃组(CA),三组均测定健康牙面菌斑pH的变化,龋活跃组另外测定龋洞内菌斑pH的变化,绘制pH随时间变化的曲线,对菌斑基线pH(pHrest)、pH下降的最低值(pHmin)、pH的下降幅度(△pH)及30 min内的曲线下面积(AUC30)进行方差分析.结果各组菌斑pH在漱糖后均下降,约5～10 min后达到最低值,随后缓慢上升,1 h左右可恢复至用糖前的水平;三组健康牙面菌斑pH的变化相似,pHrest、pH min、△pH、AUC30均无显著差异(P＞0.05);龋活跃组龋洞内菌斑pH在漱糖后的变化趋势与三组健康牙面相似,但龋洞内菌斑的pHrest明显较健康牙面低(P＜0.01),用糖后pH的下降更为明显,pHmin和AUC30均较健康牙面小(P＜0.01或P＜0.05),且恢复到用糖前基线水平所需时间亦较长.结论龋洞内的菌斑产酸力较健康牙面高,进一步验证了龋病的发生是局部菌斑产酸力增强所致.     

菌斑原位pH在判断个体龋易感性中的作用

口内牙齿表面菌斑的原位pH既能反映细菌代谢产酸的能力,也反映局部环境缓冲和转运酸的能力。本研究使用钯-微触电极测量龋活跃者(CA)和无龋者(CF)在用10％蔗糖溶液漱口前后菌斑的原位pH,以评价原位pH测定在判断个体龋易感性中的作用。结果表明,龋活跃组菌斑pH在漱糖前后各时间点均较无龋组低;龋活跃组与无龋组在漱糖后菌斑下降的最低pH相近,但龋活跃组菌斑pH回升速度慢,导致低pH水平持续时间长。上颌牙菌斑pH水平较下颌牙菌斑pH水平低,而左右侧牙菌斑pH水平大致相同,提示唾液在维持菌斑pH水平中的主导作用。     

口腔尿素分解活性与乳牙龋相关性的研究

目的：调查儿童患龋情况及其唾液和菌斑中的尿素分解活性,探讨儿童口腔内尿素酶活性与乳牙龋齿是否存在相关性。方法：采集98名3~6周岁儿童牙面菌斑和唾液样本,检查患龋情况,并将样本分为无龋、中龋和高龋组,各组对象的性别、年龄等基本信息无显著差异。采用纳氏试剂比色法测定样品中氨氮浓度,分析尿素分解活性。采用SPSS19.0,使用方差分析、相关性检验等方法统计分析调查对象的口腔患龋情况、菌斑和唾液内尿素分解活性,并分析它们之间是否存在相关性。结果：无龋组、中龋组和高龋组的菌斑样品中尿素分解活性差异具有统计学意义（P=0.007）。无龋组、中龋组和高龋组的唾液样品中尿素分解活性无显著差异。龋失补指数与菌斑尿素分解活性具有显著正相关性,Pearson相关系数为0.345;龋失补指数与唾液尿素分解活性无显著相关性。结论：本研究结果显示,口腔细菌产碱能力的下降与患龋风险的上升有相关,为今后口腔内细菌产碱能力与机体健康的相关性研究提供了新的证据。     

美蓝预防龋病的实验研究

目的：研究美蓝对变形链球菌生长、产酸代谢的作用和对体外菌斑糖酵解模型产酸代谢的作用，以及动物实验研究美蓝预防龋病的效果，为美蓝预防龋病的临床应用提供实验依据。方法：采用比浊法测定不同培养条件下变形链球菌培养液的吸光度A值；采用气相色谱法检测不同培养条件下变形链球菌培养液中有机酸的种类和数量；测定不同处理条件下体外菌斑糖酵解模型产酸液的pH值；采用Keyes龋病评分法观察美蓝对Sprague-Dawley（SD）大鼠磨牙龋的预防效果。结果：①美蓝组细菌A值低于生理盐水组，二者之间的差异具有统计学意义。②不同血清型变形链球菌的3个处理组中均可检测到有机酸的产生，葡萄糖组有机酸的总量最多，美蓝组有机酸的总量最少。③美蓝组产酸液的pH值与阴性对照组之间的差异有统计学意义，与阳性对照组之间的差异无统计学意义。④在E级和Ds级两级龋损中，美蓝组与蒸馏水组相差非常显著（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，美蓝组或氟化钠组均未发生；Dx级龋损在3组中均未出现。结论：美蓝可以抑制变形链球菌的生长、产酸代谢和菌斑的产酸代谢，能够减少SD大鼠磨牙龋的发生。     

龋易感者、无龋者和牙周病人菌斑致龋性能的体外研究

龋病是菌斑和其它因素共同作用下形成的。菌斑在发病中的作用和地位已受到有关学者的重视。国外有报导认为,菌斑内细菌种类和含量不同,决定了它们致龋能力的差异。由于口腔环境复杂,影响菌斑致龋因素很多,研究困难,故对不同人群口腔牙菌斑致龋能力还缺乏全面了解。一些学者从菌斑内细菌分离,菌斑产酸,菌斑pH变化和菌斑其它代谢活动来阐明菌斑在发病中的地位和作用,提出了许多值得重视的问题。利用菌斑中分离菌观察产酸和脱钙已有报导,由于难以模仿菌斑生态环境和不能实现各种细菌间的相互作用,故难于     

双歧杆菌在儿童口腔的分布及与儿童龋病的关系

目的探索一种可以较好地分离口腔双歧杆菌的选择性培养基,以此为基础,检测儿童口腔不同部位双歧杆菌的分布状态,初步探讨口腔双歧杆菌与儿童龋病的发生关系。方法选择70例3~6岁儿童为研究对象,其中无龋组30例,重症婴幼儿龋（S-ECC）组40例。无龋组收集唾液及唇面、邻面、面沟裂的混合菌斑;S-ECC组收集唾液、光滑面菌斑、牙面白垩斑菌斑和深龋龋坏组织。在经过改良的TPY选择性培养基中进行培养,提取细菌总DNA,用双歧杆菌特异性引物进行聚合酶链反应,对其电泳条带进行记录分析。结果S-ECC组双歧杆菌的检出率为47.5％,无龋组为0,2组间检出率的差异有统计学意义（P<0.05）。在S-ECC组儿童口腔的不同部位,双歧杆菌检出率分别为唾液27.5%、光滑面菌斑27.5%、白垩斑菌斑20.0%、龋坏组织22.5%,不同检测部位间检出率的差异无统计学意义（P>0.05）。齿双歧杆菌在S-ECC组儿童口腔不同部位的检出率分别为唾液10.0%、光滑面菌斑7.5%、白垩斑菌斑7.5%、龋坏组织10.0%,不同检测部位间检出率的差异也无统计学意义（P>0.05）。结论改良TPY双歧杆菌选择性培养基是一种适合分离口腔双歧杆菌的选择性培养基;双歧杆菌可能与S-ECC的发生相关,但其检出情况与儿童牙面的部位关系不大。     

镧、钙、氟对菌斑pH影响的实验研究

目的:对比镧、钙、氟对菌斑pH变化过程的影响,从菌斑代谢角度探讨镧的抗龋作用。方法:采用接触法连续测定含La3+、Ca2+、F-的蔗糖溶液含漱后的菌斑pH值,对pH值下降至最低所用的时间、最低pH、pH下降的幅度 ($pH)以及pH变化曲线中pH615以下的曲线下面积(AUC6.5)进行双因素方差分析。结果:8名受试对象之间各参数均无明显差别;各处理方法相比蔗糖溶液对照组导致菌斑pH下降的幅度最大,其次是含钙蔗糖溶液处理组,再次是含氟蔗糖溶液处理组及含镧蔗糖溶液处理组,后两者之间差异无显著性;各处理方法导致菌斑pH下降所需时间差异无明显性。结论:钙、镧、氟均可减小摄入蔗糖后菌斑pH的下降幅度,钙的作用最弱,镧和氟的作用相似,表明镧可干扰菌斑的产酸过程。     

2种胶姆糖对菌斑pH值的影响

目的：观察咀嚼2种胶姆糖后口腔菌斑pH值的变化情况.方法：选择8例健康受试者（年龄23～27岁,男4例,女4例）参加3次试验,每次实验开始前停止刷牙24h,在使用10%的蔗糖溶液漱口前以及漱口后5、10、15、20min,用Beetrode pH微电极测量口腔菌斑的pH值,作为基线值.1周后先测量静息pH值,再用蔗糖溶液漱口,1min后给予无糖胶姆糖咀嚼,在5、10、15、20min时间点,分别测量非咀嚼侧的菌斑pH值.1周后重复上述实验,胶姆糖改为含茶多酚胶姆糖.应用SPSS10.0统计软件包对数据进行单因素方差分析和SNK分析.结果：与基线值比较,咀嚼2种胶姆糖都能有效防止由于含漱蔗糖水导致的菌斑pH值下降,并使pH值维持在静息pH值以上.2种胶姆糖之间无显著性差异（P＞0.05）.结论：咀嚼2种胶姆糖均能防止菌斑pH值下降,减少患龋危险.     

人工体外菌斑模型的建立及其在评价防龋制剂防龋效果中的应用

目的：建立人工体外菌斑模型，研究美兰和洗必泰对人工体外菌斑代谢产酸的作用，探讨用人工体外菌斑模型评价防龋制剂防龋效果的可行性。方法：采用pH计分别测定不同生长时期及美兰和洗必泰处理后人工体外菌斑模型产酸液的pH值。结果：成功建立了人工体外菌斑模型；随着该模型生长时间的延长，产酸液pH降低；随着该模型在产酸液中培养时间延长，产酸液pH逐渐降低；美兰和洗必泰对生长96h人工体外菌斑代谢产酸没有明显作用，对生长48h人工体外菌斑代谢产酸有明显抑制作用。结论：用人工体外菌斑模型评价防龋制剂的防龋效果是可行的。     

四种方式局部用氟对牙菌斑产酸力的影响

目的探讨氟化物对含漱糖溶液后菌斑产酸力的影响，以期为合理、正确使用氟制剂防治龋齿提供实验依据。方法采用4种局部用氟方式，分别为含氟牙膏刷牙，含氟牙膏刷牙加每天1次0.05％氟化钠漱口液含漱，含氟牙膏刷牙加每周1次0．2％氟化钠漱口液含漱，含氟牙膏刷牙加试验时即刻使用0．2％氟化钠漱口液含漱。采用微型pH电极接触法检测使用氟化物后菌斑pH在含漱蔗糖溶液后1h内的变化；同时用分光光度计法检测菌斑内变形链球菌的含量。结果只有当含漱蔗糖的同时给予氟化物才能有效抑制菌斑pH下降，在含漱后各时间点菌斑pH均未发生明显变化，维持在6，0以上；而其他方式用氟后菌斑pH仍可下降至临界值5.5以下；4种用氟方式对菌斑内变形链球菌的含量无明显影响。结论氟化物可抑制菌斑内的产酸代谢活动，但这种抑制作用受菌斑内氟离子浓度的影响；在含漱糖溶液的同时给予氟可有效地抑制菌斑内酸的形成，降低菌斑的产酸力。     

The effect of increased mastication by daily gum-chewing on salivary gland output and dental plaque acidogenicity.

The effect of increased mastication on plaque metabolism and salivary gland function was determined in 11 human subjects who chewed a sugarless gum for ten minutes of each waking hour for two weeks. Prior to and at the conclusion of the gum-chewing regimen, unstimulated whole saliva and 2% citric-acid-stimulated parotid saliva were collected. Flow rates, pH, and buffer capacity were determined on all saliva samples. In addition, parotid saliva was analyzed for protein concentration and the proteins further studied by SDS-PAGE. The plaque pH response to a 10% sucrose rinse was also measured before and after the regimen. Significant increases were observed in the pH and buffer capacity of unstimulated whole saliva as were similar increases in the flow rate, pH, and buffer capacity of stimulated parotid saliva. Protein concentrations and profiles remained unaffected. In addition, the resting plaque pH and minimum plaque pH reached after a sucrose challenge were both raised significantly, with a significant reduction in the cH area. The results of this study indicate that increased masticatory effort by frequent consumption of sugar-free chewing gum over a prolonged time period resulted in a functional increase in the output of stimulated parotid saliva, as well as in increases in pH and buffer capacity of whole and parotid saliva, which may help to reduce plaque acidogenicity.     

Influence of short-term sucrose exposure on plaque acidogenicity and cariogenic microflora in individuals with different levels of mutans streptococci

The aim was to study the short-term effect of a varying sucrose exposure on plaque acidogenicity and cariogenic microflora in two groups of subjects with different levels of mutans streptococci (MS). Eight subjects with low (<10(4)) and 8 with high (>10(6)) numbers of MS per millilitre saliva participated. Three 7-day test periods were conducted. During two of these, the subjects rinsed either 5 or 10 times daily with 10% sucrose; the third period without any mouth rinses served as control. The subjects refrained from oral hygiene during the last 3 days of each test period. On day 7, the following parameters were measured: plaque pH after a sucrose rinse, numbers of MS, Streptococcus sanguis and lactobacilli in saliva, percent MS in plaque and plaque index. The results revealed that plaque acidogenicity was more pronounced for the high-MS group compared to the low-MS group after all three test periods, i.e. lower resting pH, deeper pH falls and a lower final pH. For both groups, the greatest pH-lowering capacity of plaque was found after the period with 10 sucrose rinses/day. An increase in bacterial counts was noted for both groups during the test periods with the 5- and 10-time rinse regimen; this increase was larger for the high-MS group compared to the group with low MS counts. The highest plaque index was, irrespective of the test period, found for the high-MS group.     

Dental plaque as a biofilm: a pilot study of the effects of nutrients on plaque pH and dentin demineralization

Direct or in situ methods (e.g., confocal microscopy, microsensors) are used to study non-oral biofilms for almost two decades, and they have recently been introduced in the research of dental plaque. We combined a pH microsensor technique and transversal microradiography (TMR) in a pilot study where the effects of nutrient availability on plaque acidogenicity and on the development of caries-like lesions were assessed. One volunteer accumulated dental plaque for 7 days in 0.2-mm-wide and 0.8-mm-deep dentin grooves at four conditions: (1) saliva only, (2) 8 x 5 min/day dipping in 10% sucrose solution, (3) 7 x 5 min/day consumption of sweet cookies plus one meal/day, and (4) subject's regular diet. Plaque pH versus time and depth profiles in the grooves were recorded ex vivo before and after sugar challenge. 'Saliva' plaque responded to sugar with slow pH decrease--minimum pH 5.6-5.8 was reached after 30 min, while sugar dipping resulted in metabolically active plaque (minimum pH 5.3-5.5 within 4-8 min). TMR analysis revealed no demineralization after these two periods. Metabolically active plaque leading to distinct lesions resulted from frequent plaque exposure to diets rich in starch and carbohydrates (groups 3 and 4). These findings strengthen the view that the plaque acidogenicity does not necessarily reflect cariogenicity, and that retention of food components may account for increased cariogenicity at plaque retention sites in the mouth.     

Effects of mouthrinses containing essential oils and alcohol-free chlorhexidine on human plaque acidogenicity

The aim of this in vivo study was to evaluate the effect of two antimicrobial mouthrinses on dental plaque acidogenicity after a sucrose challenge. Twenty subjects, with a mean age of 59 years, participated in a double-blind intraindividual randomized study. Three mouthrinses were used in 16-day rinsing periods in addition to their regular mechanical oral hygiene: a solution with essential oils (EO), solution with alcohol-free chlorhexidine (CHX) and water (negative control). The three test periods were separated by 3-month washout periods. Changes in plaque acidogenicity were evaluated after a sucrose challenge at day 0 (baseline) and at day 17 of each mouthrinse period using the microtouch method. Both CHX and EO resulted at day 17 in statistically significant less attenuated pH falls compared to the water rinse. The CHX mouthrinse resulted in the least pronounced pH values compared with EO (ns) during the whole 30-min period. When calculated as area under the curve (AUC), significantly lower values (AUC_6.2 ) were found for CHX and EO at day 17 compared to day 0. A significant difference for AUC_6.2 between CHX and water was found at day 17. No statistically significant differences were found for any of the comparisons with AUC_5.7. The results from this study indicate that both the essential oils and the alcohol-free chlorhexidine reduced plaque acidogenicity after a sucrose challenge. Large interindividual variations were observed.     

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.     

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

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 effect of a single application of 40% chlorhexidine varnish on the numbers of salivary mutans streptococci and acidogenicity of dental plaque

The relationship between the numbers of salivary mutans streptococci and the acid production in dental plaque after a single application of the 40% chlorhexidine varnish EC40 has been studied. Thirteen healthy subjects were treated with EC40 varnish. Saliva samples were taken before and up to 12 weeks after treatment to count mutans streptococci and lactobacilli. At the same time points plaque samples were taken before and after sucrose challenge and analyzed for protein and organic acid. Suppression of salivary mutans streptococci was observed together with a reduced production of lactic acid in sucrose-challenged dental plaque in 9 subjects while inhibition of acid production without significant suppression of mutans streptococci was observed in the other 4 participants. The duration of the effects differed among the individuals but never exceeded 6 weeks. We conclude that a prolonged suppression of mutans streptococci and acid production was not achieved by a single treatment with EC40 varnish in all subjects. Moreover, reduced acidogenicity of dental plaque after chlorhexidine treatment was not necessarily predicted by suppression of mutans streptococci in saliva.     

Effects of processed cheese on human plaque pH and demineralization and remineralization

This two-part study was undertaken to examine the effects of processed cheese on human plaque pH and de- and remineralization of enamel and root lesions in a human in situ caries model system. In the first part of the study the selected processed cheese (Kraft American Singles Processed Cheese Food) was eaten alone and followed by a 10% sucrose rinse after the acidogenicity of the plaque was demonstrated. A 10% sucrose rinse alone resulted in a mean minimum pH of 4.26. The cheese alone showed a mean minimum pF of 6.32 and cheese followed by sucrose resulted in a mean minimum pH of 6.48. The plaque pH of cheese eaten alone stayed at pH above 5.7 (the "safe for teeth" level). Cheese consumption also prevented the acid challenge when followed by sucrose. The second part of the study utilized the thin-sections of artificially created caries-like lesions on enamel and root, and sound root sections. One-month periods were used in a cross-over design to examine the effect of eating the cheese q.i.d. Polarized light microscopy was used to determine changes in the size of lesion areas. The addition of the processed cheese to the diet resulted in statistically significant reductions in enamel lesion size as well as a reduction in progression of root lesions. Lesions created on the sound root surfaces were approximately one-third the size of those created during the control period. This study indicates that processed cheese is hypoacidogenic, anti-acidogenic, and prevents demineralization as well as enhances remineralization.     

Effect of an essential oil mouthrinse, with and without fluoride, on plaque metabolic acid production and pH after a sucrose challenge

This clinical study evaluated the effect of rinsing with an essential oil-containing antiseptic mouthrinse, with or without 100 mg/kg fluoride ion, on the plaque metabolic acid production and plaque pH response after a sucrose challenge. This observer-blind, randomized study used a three-way crossover design. Twenty-four subjects rinsed with 20 ml of one of the following rinses: (1) essential oil (EO) mouthrinse, (2) essential oil mouthrinse plus 100 mg/kg fluoride, or (3) negative control, for 30 s, twice daily for 16 days. On day 17, 1 h after the last mouthrinse, subjects rinsed with 20 ml of mass fraction 10% sucrose solution for 1 min. Seven minutes after the sucrose challenge, supragingival plaque was collected from molar and premolar teeth. Plaque pH and metabolic acid ions were analyzed using a micro pH electrode and capillary electrophoresis, respectively. The results showed that after EO mouthrinse dental plaque produced 36% less lactate, 36% less acetate and 44% less propionate than after the negative control rinse. The dental plaque also exhibited a pH 0.42 unit higher after EO rinse than after the negative control rinse. These results were not affected by the addition of 100 mg/kg fluoride to the EO mouthrinse. From these results we concluded that this EO antiseptic mouthrinse, with or without fluoride ion, is effective in reduction of plaque acidogenicity after a sucrose challenge.     

菌斑pH值、游离钙和总蛋白水平与根龋易感性的关系

目的　分析菌斑液成分的动态变化与根龋易感性的关系。方法　比较无根龋组和有根龋组根面牙菌斑液在糖溶液漱口前后 ,所测定pH值、游离钙 (微电极法 )和总蛋白水平 (分光光度法 )的差异。结果　静止状态下 ,无根龋组和有根龋组的pH值 (无根龋组 6 2 4± 0 74,有根龋组 5 96±0 70 )和游离钙 [无根龋组 (0 6 0± 0 46 )mmol/L ,有根龋组 (0 89± 0 5 4)mmol/L]两项指标差异无统计学意义 ;糖漱口后 ,有根龋组的pH(5 14± 0 19)和游离钙 [(1 73± 0 74)mmol/L]水平均低于无根龋组[pH 5 2 8± 0 16 ,游离钙 (2 73± 1 2 5 )mmol/L],差异有统计学意义。总蛋白水平与游离钙含量之间没有相关性。同一个体牙根面与冠面之间菌斑液的三项指标均有显著的相关关系。结论　有根龋组的菌斑液有较强的致龋倾向 ,在细菌酵解糖产酸方面 ,牙根面 (牙骨质 )菌斑与牙冠面 (牙釉质 )菌斑无根本差别