The effects of orthodontic bonding steps on biofilm formation of Streptococcus mutans in the presence of saliva

Abstract

Objective. To investigate the effects of various orthodontic bonding steps on biofilm formation of Streptococcus mutans in the presence of saliva. Materials and methods: Hydroxyapatite (HA) and orthodontic adhesive (AD) disks were prepared to a uniform size. HA disks were etched with 37% phosphoric acid gel in the etched group (HE). In the primed group (HP), Transbond XT primer was applied to the etched HA surface and light-cured. For biofilm formation, Streptococcus mutans was grown on each specimen in a biofilm medium with either glucose or sucrose in the presence of fluid-phase UWS (F-UWS) or surface adsorbed saliva (S-UWS). The adherent bacteria were quantified by enumeration of the total viable counts of bacteria. Biofilms formed on each surface were examined by scanning electron microscopy. Results. When glucose was used, both F-UWS and S-UWS suppressed biofilm formation of S. mutans. Compared to HA and HE, biofilm formation was significantly inhibited on HP and AD in the presence of glucose. Biofilm-forming patterns that were inhibited by saliva were restored in a sucrose-containing medium. F-UWS promoted biofilm formation on HA and HE, while S-UWS significantly promoted biofilm formation on HP. S. mutans developed biofilm better on HA and HE than on AD when sucrose was used as the sole carbohydrate source. Conclusions. This study suggests that the biofilm development by S. mutans is significantly influenced by the orthodontic bonding procedure. Biofilm formation of S. mutans was inhibited on AD more than other surfaces, irrespective of the presence of saliva or a carbohydrate source.     

The Effects of Surface Roughness of Composite Resin on Biofilm Formation of Streptococcus mutans in the Presence of Saliva

SUMMARY The purpose of this study was to investigate the effects of surface roughness of resin composite on biofilm formation of Streptococcus mutans in the presence of saliva. To provide uniform surface roughness on composites, disks were prepared by curing composite against 400-grit silicon carbide paper (SR400), 800-grit silicon carbide paper (SR800), or a glass slide (SRGlass). The surface roughness was examined using confocal laser microscopy. For biofilm formation, S. mutans was grown for 24 hours with each disk in a biofilm medium with either glucose or sucrose in the presence of fluid-phase or surface-adsorbed saliva. The adherent bacteria were quantified via enumeration of the total viable counts of bacteria. Biofilms were examined using scanning electron microscopy. This study showed that SR400 had deeper and larger, but fewer depressions than SR800. Compared to SRGlass and SR800, biofilm formation was significantly increased on SR400. In addition, the differences in the effect of surface roughness on the amount of biofilm formation were not significantly influenced by either the presence of saliva or the carbohydrate source. Considering that similar differences in surface roughness were observed between SR400 and SR800 and between SR800 and SRGlass, this study suggests that surface topography (size and depth of depressions) may play a more important role than surface roughness in biofilm formation of S. mutans .     

Effects of human milk on adhesion of Streptococcus mutans to saliva-coated hydroxyapatite in vitro

Adhesion of bacteria to pellicle-coated tooth surfaces is the first step in biofilm formation on teeth. The aim of this study was to explore whether human milk prevents or promotes adhesion of cariogenic Streptococcus mutans to saliva-coated hydroxyapatite (HA) using an in vitro model system. S. mutans binding to HA coated with human parotid saliva (s-HA) or human milk was studied, in addition to binding inhibition to s-HA by human milk. S. mutans did not bind to HA coated with milk. S. mutans binding to s-HA was inhibited by milk from 15 (71 %) of 21 women, whereas milk from the remaining 6 mothers enhanced binding of S. mutans to s-HA. Inhibition of S. mutans binding correlated with bacterial binding to s-HA (r = 0.76). Human milk does not mediate adhesion of S. mutans to HA in vitro, but affects adhesion in an individually varying fashion. Phenotypic variations in milk and saliva glycosylation may explain the inhibitory capacity and possibly affect susceptibility to colonization by S. mutans in childhood.     

Involvement of antigen I/II surface proteins in Streptococcus mutans and Streptococcus intermedius biofilm formation

BACKGROUND/AIM: Dental diseases are caused by microorganisms organized in biofilms. Streptococcus mutans and Streptococcus intermedius are commensals of the human oral cavity. S. mutans is associated with caries, whereas S. intermedius is associated with purulent infections. Oral streptococci including S. mutants and S. intermedius express a family of surface proteins termed antigen I/II (Ag I/II). Ag I/II is implicated in adhesion; however, its role in biofilm formation has not yet been investigated. METHODS: By using isogenic Ag I/II-deficient mutants of S. mutans and S. intermedius we studied the influence of Ag I/II on in vitro biofilm formation. Biofilm was quantified in polystyrene microtiter plates and visualized by scanning electron microscopy. Ag I/II expression in planktonic and biofilm cells, as well as in the presence or absence of saliva was investigated by immunoblotting. RESULTS: In the presence of saliva, the Ag I/II-deficient mutants formed 65% less biofilm than the wild-types. In the absence of saliva, no difference was observed in S. mutans, whereas the S. intermedius Ag I/II mutant formed 41% less biofilm. Ag I/II expression was reduced in the presence of saliva. No differences in expression were observed between biofilm and planktonic cells. CONCLUSION: The results indicated that Ag I/II may be important during biofilm formation particularly in the presence of saliva. These findings may provide useful information regarding the importance of Ag I/II in biofilm formation and in the search of new strategies to control biofilm-mediated infections.     

Effect of Weissella cibaria isolates on the formation of Streptococcus mutans biofilm

The objective of this study was to isolate and identify lactic acid bacteria able to inhibit the in vitro formation of Streptococcus mutans biofilm as well as the in vivo formation of oral biofilm. Two strains, CMS1 and CMS3, exhibiting profound inhibitory effects on the formation of S. mutans biofilm and the proliferation of S. mutans, were isolated from children's saliva and identified as Weissella cibaria by 16S rDNA sequencing. The water-soluble polymers produced from sucrose by the W. cibaria isolates also inhibited the formation of S. mutans biofilm. According to the results of thin-layer chromatographic analysis, the hydrolysates of water-soluble polymers produced by the isolates were identical to those of dextran, forming mostly alpha-(1-6) glucose linkages. In the clinical study, the subjects mouthrinsed with a solution containing W. cibaria CMS1 evidenced plaque index reduction of approximately 20.7% (p < 0.001). These results indicate that the W. cibaria isolates possess the ability to inhibit biofilm formation, both in vitro and in vivo.     

变异链球菌LuxS基因缺陷突变株的构建及其生物膜结构的初步观察研究

目的:通过同源重组法构建变异链球菌LuxS基因缺陷突变菌株,比较其与变异链球菌UA159标准株在生物膜形成上的差异。方法:运用基因同源重组方法将氯霉素抗性基因(Cmr)与LuxS基因上下游区域的2个基因片段按一定顺序重组到PUC载体的多克隆位点中,构建出带氯霉素抗性标志的重组质粒,将载体质粒转化到含完整LuxS基因的变异链球菌UA159中,利用氯霉素抗性筛选出LuxS基因缺陷的突变株,并利用聚合酶链式反应(PCR)和哈氏弧菌发光实验进行检测。以釉质磨片为载体,在扫描电镜下观察上述两菌株含有20 g/L葡萄糖、20 g/L蔗糖的乳酪消化胨酵母(TPY)液体培养基中形成24 h的生物膜。结果:PCR基因扩增结果显示:突变株LuxS基因已被Cmr基因完全替换,成功的构建了变异链球菌LuxS基因突变株,并且突变株不能诱导哈氏弧菌BB170的生物发光。当用葡萄糖作为补充糖源时,变异链球菌UA159标准株和LuxS基因突变株所形成的生物膜表现型未见明显差异;而用蔗糖作为补充糖源时,两菌株所形成的生物膜有明显不同,UA159生物膜相对平滑均质,而LuxS基因突变株生物膜呈松散的蜂房状,基质间有较大的间隙,形成较大的团簇状菌落。结论:成功构建出LuxS基因缺陷的变异链球菌突变株,与变异链球菌UA159标准株其生物膜结构发生改变,提示LuxS会影响变异链球菌生物膜的形成。     

Effects of oral streptococci on biofilm formation by cariogenic bacteria in dual species cultures

The effects of oral commensal streptococci (Streptococcus sanguinis, Streptococcus gordonii, Streptococcus mitis, and Streptococcus salivarius) on biofilm formation by cariogenic mutans streptococci (Streptococcus mutans and Streptococcus sobrinus) were investigated. Cell suspensions were cultured on 96-well microtiter plates coated with or without salivary components (SC), and in flow cell systems coated with SC in tryptic soy broth including 0.25% sucrose without dextrose (TSB). The resultant biofilm formations were stained using safranin or a LIVE/DEAD BacLight Viability Kit, and examined with absorbance at 492 nm or using confocal laser scanning microscopy. Mutans streptococci and S. sanguinis biofilms were formed significantly on the polystyrene surfaces in TSB. Further, in combination cultures, S. sanguinis formed a sufficient biofilm when cultured with S. mutans. However, when S. sanguinis was cultured with S. sobrinus, biofilm formation was slightly inhibited. S. gordonii also inhibited biofilm formation in the culture with S. sobrinus, but not when cultured with S. mutans. S. mitis and S. salivarius collapsed the biofilm morphology and inhibited volume development in some conditions when cultured with S. mutans or S. sobrinus. Biofilm formation by mutans streptococci was challenged and collapsed on the whole by culturing with each of the other oral streptococci. These results indicate that co-culturing of multiple species of mutans streptococci and other oral streptococci has physical effects related to previous attachment and colonization on the surface, as well as biological effects to regulate biofilm formation.     

Genotypic and phenotypic analysis of S. mutans isolated from dental biofilms formed in vivo under high cariogenic conditions

The oral cavity harbors several Streptococcus mutans genotypes, which could present distinct virulence properties. However, little is known about the diversity and virulence traits of S. mutans genotypes isolated in vivo under controlled conditions of high cariogenic challenge. This study evaluated the genotypic diversity of S. mutans isolated from dental biofilms formed in vivo under sucrose exposure, as well as their acidogenicity and aciduricity. To form biofilms, subjects rinsed their mouths with distilled water or sucrose solution 8 times/day for 3 days. S. mutans collected from saliva and biofilms were genotyped by arbitrarily-primed PCR. Genotypes identified in the biofilms were evaluated regarding their ability to lower the suspension pH through glycolysis and their acid susceptibility and F-ATPase activity. Most subjects harbored only one genotype in saliva, which was detected in almost all biofilm samples at high proportions. Genotypes isolated only in the presence of sucrose had higher acidogenicity than those isolated only in the presence of water. Genotypes from biofilms formed with sucrose were more aciduric after 30 and 60 min of incubation at pH 2.8 and 5.0, respectively. The present results suggest that biofilms formed under high cariogenic conditions may harbor more aciduric and acidogenic S. mutans genotypes.     

The cariogenic characters of xylitol-resistant and xylitol-sensitive Streptococcus mutans in biofilm formation with salivary bacteria

Streptococcus mutans metabolize carbohydrates, such as glucose and sucrose, to produce acid and enhance biofilm formation with the early colonizing bacteria to induce dental caries. Xylitol has been used as a reliable substitute for carbohydrate to inhibit the acid production of S. mutans. However, long-term xylitol consumption leads to the emergence of xylitol-resistance in S. mutans. The aim of this study was to investigate the cariogenic trait of Xylitol-resistant (X(R)) S. mutans using biofilm formation and coaggregation of xylitol-sensitive (X(S)) and X(R) S. mutans with salivary bacteria and their glucosyltransferases expression. When X(S) or X(R) S. mutans were incubated in brain heart infusion broth with bacteria from human saliva, X(R)S. mutans exhibited reduction in biofilm formation in comparison to X(S) S. mutans. The coaggregation between X(R) S. mutans and S, gordonii, S. mitis, S. oralis or S. sanguinis was less pronounced than that of X(S) S. mutans in the presence of sucrose. However, there was no difference in the coaggregation between X(R) and X(S) S. mutans in the sucrose-free condition. The level of gtfB and gtfC mRNA expression of X(R) S. mutans was lower than that of X(S) S. mutans, whilst the level of gtfD mRNA expression did not differ between the two strains. The reduction of biofilm formation in X(S) S. mutans due to decrease in glucosyltransferases expression suggests that X(R) S. mutans may be less cariogenic than X(S) S. mutans.     

Deletion of gtfC of Streptococcus mutans has no influence on the composition of a mixed-species in vitro biofilm model of supragingival plaque

Glucosyltransferases from Streptococcus mutans are thought to play an important role in bacterial adherence to the tooth surface. The goal of the present study was to determine the effect of the deletion of the gtfC gene, which encodes a glucosyltransferase that catalyses primarily the formation of insoluble glucan (mutan), on colonization of S. mutans in a mixed-species biofilm model of supragingival plaque. A gtfC deletion mutant of S. mutans UA159 grew poorly in biofilms on a polystyrene surface in Todd–Hewitt medium containing sucrose, but biofilm formation in the semi-defined fluid universal medium (FUM) was not affected. The S. mutans gtfC mutant colonized with the same efficiency as the wild-type strain when grown together with five other species in a mixed-species biofilm on hydroxyapatite in a mixture of FUM and saliva with pulses of sucrose and showed the same ability to demineralize enamel in vitro . Colonization of mutant and wild-type strains was also equal in an association experiment in specific-pathogen-free rats. However, the gtfC mutant gave rise to more dentinal fissure lesions and smooth surface caries than the wild-type strain; this could be caused by a change in diffusion properties as a result of to the lack of mutan.     

Effect of 0.4% stannous fluoride gel on Streptococci mutans in relation to elastomeric rings and steel ligatures in orthodontic patients.

BACKGROUND: Patients with fixed orthodontic appliances often experience an absolute increase in the number of Streptococci mutans colony-forming units (cfu). The aim of this investigation was to study the development of biofilm and S. mutans cfu in connection with stainless steel ligatures and elastomeric rings in orthodontic patients treated with and without 0.4% stannous fluoride gel (SFG). MATERIAL: Forty-seven patients were divided into 2 groups: those treated with 0.4% SFG for 4 minutes (experimental) and those without 0.4% SFG (control). In each patient, elastomeric rings were used for ligation on 1 side of the dental arch midline, and stainless steel ligatures were used on the opposite side. Saliva samples were collected before and after appliance placement. At 15 and 30 days after appliance placement, biofilm samples from the stainless steel ligatures and the elastomeric rings were collected and subjected to microbiologic procedures and scanning electron microscopy (SEM) analysis. RESULTS: The numbers of S. mutans cfu in the saliva and biofilm were not statistically different between the teeth fitted with elastomeric rings and stainless steel ligatures, or between the experimental and control groups. SEM analysis showed biofilm formation on both ligature ties. CONCLUSIONS: Topical application of 0.4% SFG in orthodontic patients with elastomeric rings or stainless steel ligatures does not cause a significant decrease in S. mutans cfu in the saliva and biofilm.     

Adhesion of Streptococcus mutans to different types of brackets

OBJECTIVE: To examine the difference in the adhesion of Streptococcus mutans to three different types of orthodontic brackets and the effect of the presence of an early salivary pellicle and Streptococcus sanguis on adhesion. MATERIALS AND METHODS: Three adhesion experiments were performed using stainless steel, ceramic, and plastic orthodontic brackets. In the first experiment a clinical strain of S mutans adhered to the three different types of brackets (n = 6 for each). For the second, the brackets were treated with saliva before adhesion of S mutans (n = 6 per type of bracket). Finally, the third experiment concerned saliva coated brackets (n = 6 per type of bracket), but before S mutans, S sanguis bacteria were allowed to adhere. The bacteria were always allowed to adhere for 90 minutes in all the experiments. Adhesion was quantitated by a microbial culture technique by treating the brackets with adhering bacteria with trypsin and enumerating the total viable counts of bacteria recovered after cultivation. RESULTS: There were consistently no differences in the adherence to stainless steel, ceramic, or plastic brackets. The presence of an early salivary pellicle and S sanguis reduced the number of adhering S mutans to all three types of brackets. CONCLUSIONS: Adhesion of bacteria to orthodontic brackets depends on several factors. The presence of a salivary pellicle and other bacterial species seem to have a significant effect on the adhesion of S mutans, reducing their numbers and further limiting any differences between types of brackets.     

蔗糖环境对寡发酵链球菌与变异链球菌双菌种生物膜形成的影响

目的探讨蔗糖环境对寡发酵链球菌与变异链球菌双菌种生物膜形成的影响,并与血链球菌和变异链球菌的双菌种生物膜形成进行比较。方法运用菌落计数法观察蔗糖环境下唾液包被的玻璃生物模型中单/双菌株寡发酵链球菌,变异链球菌和血链球菌24 h生物膜形成情况;运用激光共聚焦显微镜观察蔗糖环境下寡发酵链球菌,变异链球菌和血链球菌单/双菌株生物模型中24h生物膜形成厚度。结果无糖环境下,单菌株模型中,菌落数:血链球菌(55.67±5.36)>变异链球菌(53.48±2.63)(P>0.05)>寡发酵链球菌(46.24±2.34)(P<0.05);生物膜厚度:血链球菌(17.23±3.82)>变异链球菌(15.16±4.21)(P>0.05)>寡发酵链球菌(10.54±4.37)(P<0.05)。双菌株模型中,变异链球菌菌落数降低幅度:血链球菌组>寡发酵链球菌组(P<0.05)。生物膜厚度:血链球菌组(8.12±2.82)<寡发酵链球菌组(11.27±3.55)(P<0.05)。蔗糖环境下,单菌株模型中,菌落数:变异链球菌(58.54±2.74)>血链球菌(51.87±5.35)>寡发酵链球菌(48.57±3.05)(P<0.05)生物膜厚度:变异链球菌(20.63±5.71)>血链球菌(13.37±4.93)>寡发酵链球菌(12.45±4.62)(P<0.05)双菌株模型中;变异链球菌菌落数降低幅度,寡发酵链球菌组>血链球菌组(P<0.05),生物膜厚度:寡发酵链球菌组(6.67±2.19)<血链球菌组(10.45±2.72)(P<0.05)。结论外界糖环境影响寡发酵链球菌和血链球菌对变异链球菌的抑制作用,蔗糖环境下,寡发酵链球菌的抑制作用强于血链球菌。     

The effect of cocoa polyphenols on the growth, metabolism, and biofilm formation by Streptococcus mutans and Streptococcus sanguinis

The aim of this study was to determine if cocoa polyphenols could interfere with biofilm formation by Streptococcus mutans or Streptococcus sanguinis, and reduce acid production from sucrose by S. mutans. The antimicrobial activity of cocoa polyphenols was assessed against cariogenic (S. mutans) and health-associated (S. sanguinis) species by minimum inhibitory concentration assays. Cocoa polyphenol dimer, tetramer, and pentamer inhibited the growth of S. sanguinis, whereas the growth of S. mutans was unaffected. However, pretreatment of surfaces with cocoa polyphenol pentamer (35 microM) reduced biofilm formation by S. mutans at 4 and 24 h, whereas the effects on S. sanguinis were less consistent. In contrast, brief exposure of preformed biofilms to pentamer either had no significant effect or resulted in increased counts of S. mutans under certain conditions. Cocoa polyphenol pentamer (500 microM) significantly reduced the terminal pH, and inhibited the rate of acid production by S. mutans at pH 7.0. In conclusion, cocoa polyphenols can reduce biofilm formation by S. mutans and S. sanguinis, and inhibit acid production by S. mutans.     

Saliva-promoted adhesion of Streptococcus mutans MT8148 associates with dental plaque and caries experience

Colonization of enamel surfaces by Streptococcus mutans is thought to be initiated by the attachment of bacteria to a saliva-derived conditioning film (acquired pellicle). However, the clinical relevance of the contribution of saliva-promoted S. mutans adhesion in biofilm formation has not yet been fully elucidated. The aim of this study was to correlate saliva-promoted S. mutans adhesion with biofilm formation in humans. We correlated all measurements of salivary factors and dental plaque formation in 70 healthy subjects. Dental plaque development after thorough professional teeth cleaning correlated positively with S. mutans adhesion onto saliva-coated hydroxyapatite pellets and the glycoprotein content of either parotid or whole saliva. Saliva-promoted S. mutans adhesion and glycoprotein content were also positively correlated with each other in parotid and whole saliva. By contrast, neither salivary mutans streptococci, Lactobacillus nor Candida correlated with biofilm formation. Parotid saliva-mediated S. mutans adhesion was significantly higher in 12 caries-experienced (CE) subjects than in 9 caries-inexperienced (CI) subjects. Salivary S. mutans adhesion was significantly less (p < 0.01) in the CI group than in the CE group. In conclusion, the present findings suggest the initial S. mutans adhesion, modulated by salivary protein adsorption onto the enamel surface, as a possible correlate of susceptibility to dental plaque and caries.     

Effect of nutrients on defined bacterial plaques and Streptococcus mutans C67-1 implantation in a model mouth

Actinomyces viscosus WVU 627, Streptococcus oralis LPA-1 and Veillonella dispar OMZ 193 were cocultured on teeth in a model mouth for 66 h. Synthetic saliva containing bovine salivary glycoprotein supported bacterial growth, although the delivery of an intermittent nutrient supplement, containing 1% (w/v) glucose or sucrose, gave greater bacterial cell and viable counts. When Streptococcus mutans C67-1 was super-inoculated onto 24-hour mixed plaques, it became established under all regimens, but there was pronounced colonization resistance. With saliva only, the proportion of S. mutans at 66 h was less than 0.5% of the total cultivable microflora. When a glucose supplement was delivered for 1 h every 6 h, S. mutans attained a final proportion of 2.4%. With sucrose, both S. mutans C67-1 and its non-cariogenic glucan-deficient mutant, C67-25, attained similar proportions of 15-20%. These experiments indicate how this model can be used to study the factors influencing colonizing ability and microbial interactions in biofilms under controlled conditions.     

Interaction of structural isomers of sucrose in the reaction between sucrose and glucosyltransferases from mutans streptococci

Structural isomers of sucrose, i.e. disaccharides composed of glucose and fructose molecules with different glucosidic linkages, were examined for their effect on the reaction between sucrose and various glucosyltransferases (GTases) from Streptococcus mutans MT8148 and Streptococcus sobrinus 6715. Trehalulose (alpha 1-1), turanose (alpha 1-3), maltulose (alpha 1-4), and palatinose (alpha 1-6) were used as the sucrose analogues. Mutans streptococci were found not to utilize these sucrose analogues. Analysis of enzymatic products of GTase and sucrose with thin layer chromatography clearly revealed that glucan synthesis from [14C]sucrose by the various purified GTase preparations from S. mutans and S. sobrinus was inhibited in the presence of these sucrose analogues except turanose, resulting in the release of increased amounts of [14C]fructose and [14C]oligosaccharides. It was also found that the fructose residues in the oligosaccharides were derived from those of sucrose analogues but not sucrose itself. The Lineweaver-Burk plots of the substrate saturation kinetics of GTase vs sucrose indicated increased Km and Vmax in the presence of sucrose analogue, as compared with sucrose alone. Finally, these sucrose analogues except turanose inhibited sucrose dependent cellular adherence of S. sobrinus 6715 to a glass surface, while they scarcely inhibited the adherence of S. mutans MT8148. Among the analogues, maltulose appeared the most effective inhibitor against GTases in general.     

氟磷灰石晶体膜对变异链球菌早期粘附和生物膜形成的作用

目的:研究牙本质表面再生氟磷灰石晶体膜(Fluorapatite crystal film,FACF)对变异链球菌(S.mutans)早期粘附和生物膜形成的作用。方法:近生理条件下(37℃,1 atm,pH 6.0~7.4),在牙本质表面沉积FACF,并将牙本质、羟基磷灰石(hydroxyapatite,HA)和氟磷灰石(fluorapatite,FA)样本作为对照组,SEM观察表面形貌。激光共聚焦显微镜(CLSM)和SEM观察牙本质和FACF表面S.mutans的早期粘附情况。HA、FA、牙本质及FACF表面培养S.mutans生物膜,CLSM观察并计算生物膜量。结果:FACF厚5~10μm,晶体呈标准的六棱柱样,排列规则紧密,直径0.5~1.0μm。FACF表面S.mutans粘附量显著少于牙本质(P<0.05),单位面积生物膜量显著低于HA、FA及牙本质(P<0.05),且阻挡了S.mutans向牙本质小管内生长。结论:在近生理条件下,可在牙本质表面再生出厚5~10μm的FA有序致密晶体膜,该层晶体结构可减少S.mutans的初期粘附及生物膜的形成,并对S.mutans向牙本质小管内生长起到物理屏障作用。     

Prevalence of Helicobacter pylori in the adolescent oral cavity

Background

Helicobacter pylori (HP) infection usually occurs in childhood. While there are various studies on the prevalence of HP in dental plaque, ours is the first to analyze its prevalence during orthodontic therapy and its interaction with competitive bacteria in adolescents.

Subjects and methods

The prevalence of HP was examined before and during the first 12?weeks of orthodontic therapy with fixed appliances in 11?patients with a mean age of 12.7?years. A total of 93?plaque samples were analyzed using PCR. The data acquired at every consultation were the following: PCR analysis of dental plaque and ¹³C urea breath tests for HP, quantitative analyses of saliva for Lactobacilli and Streptococcus mutans, the interproximal plaque index (API), and sulcus bleeding index (SBI).

Results

The prevalence of HP in plaque was 82% before orthodontic therapy, dropping to 54% during therapy (t test, p??0.05). In contrast to HP??s prevalence, the Lactobacilli count rose (p??0.05). The number of Streptococcus mutans bacteria in saliva decreased during orthodontic therapy (p??0.05).

Conclusion

The prevalence of HP in dental plaque amounted to 82%. Orthodontic treatment did not reduce its prevalence. The prevalence of Lactobacilli was inversely proportional to that of HP.     

Effect of salivary biofilm on the adherence of oral bacteria to bleached and non-bleached restorative material.

OBJECTIVE: The objective of this work was to examine the effect of in vitro salivary biofilm on the adherence of oral bacteria to bleached and non-bleached restorative material (Charisma). METHODS: Charisma samples, prepared in silicon models, were treated with either 10% carbamide peroxide (CP) or 10% hydrogen peroxide (HP). After incubation with the bleaching agent for a period of one, two or three days, the samples were coated with freshly collected human saliva. The adsorption pattern of the saliva to the restorative material was determined using gel electrophoresis coupled with computerized densitometry techniques. The amount of salivary proteins adsorbed onto the treated surfaces was measured using the Bradford method. Sucrose-dependent bacterial adhesion to the salivary-coated Charisma was tested using radio-labeled Streptococcus mutans, Streptococcus sobrinus and Actinomyces viscosus. Adhesion of each bacterium to surfaces pretreated with the bleaching agents was compared with saliva coated bleached surfaces. RESULTS: The profile of salivary proteins adsorption followed a similar pattern in Charisma samples pretreated with either CP or HP or untreated samples. However, the total amount of salivary proteins adsorbed onto the samples decreased after bleaching with CP or HP. Salivary biofilm, coating the surface of the restorative material, significantly decreased sucrose-dependent adhesion of Streptococcus sobrinus and Streptococcus mutans to the bleached and non-bleached surfaces, compared to non-coated specimens (p < 0.05). Saliva had a minor effect on adhesion of Actinomyces viscosus. SIGNIFICANCE: Our study demonstrates the importance of salivary biofilm in controlling adhesion of oral bacteria to restorative material pretreated with bleaching agents or untreated.