Supragingival Plaque Formation Research Articles

Strategies to Combat Caries by Maintaining the Integrity of Biofilm and Homeostasis during the Rapid Phase of Supragingival Plaque Formation.

Bacteria in the oral cavity, including commensals and opportunistic pathogens, are organized into highly specialized sessile communities, coexisting in homeostasis with the host under healthy conditions. A dysbiotic environment during biofilm evolution, however, allows opportunistic pathogens to become the dominant species at caries-affected sites at the expense of health-associated taxa. Combining tooth brushing with dentifrices or rinses combat the onset of caries by partially removes plaque, but resulting in the biofilm remaining in an immature state with undesirables’ consequences on homeostasis and oral ecosystem. This leads to the need for therapeutic pathways that focus on preserving balance in the oral microbiota and applying strategies to combat caries by maintaining biofilm integrity and homeostasis during the rapid phase of supragingival plaque formation. Adhesion, nutrition, and communication are fundamental in this phase in which the bacteria that have survived these adverse conditions rebuild and reorganize the biofilm, and are considered targets for designing preventive strategies to guide the biofilm towards a composition compatible with health. The present review summarizes the most important advances and future prospects for therapies based on the maintenance of biofilm integrity and homeostasis as a preventive measure of dysbiosis focused on these three key factors during the rapid phase of plaque formation.

Efficacy of 0.2% tempered chlorhexidine as a subgingival irrigant in chronic periodontitis: A randomized control trial

Introduction: Chlorhexidine (0.2%) has been considered to be clinic effective against supragingival plaque formation. It is considered as a gold standard for chemical plaque control and can reduce plaque scores effectively at different temperature, concentration and pH. Aim: To investigate the efficacy of tempered chlorhexidine over conventional 0.2% chlorhexidine as a subgingival irrigant in reduction of periodontal parameters and bacterial count. Materials and Methods: A randomized control clinical trial as conducted at I.T.S dental college, Muradnagar, Ghaziabad, India in which 20 systemically healthy patient’s sites having chronic periodontitis with pocket depth of 4-6 mm were included. Group I(test group)- ultrasonic scaling and root planning followed by tempered 0.2% chlorhexidine irrigation (maintained at 47 degree centigrade) for 20 secs at 10 sites and Group II (control group)- ultrasonic scaling root planning followed by 0.2% chlorhexidine irrigation for 20 secs at 10 sites. Plaque index (PI), gingival index (GI), probing depth (PD) were recorded and plaque samples was taken for the count of colony forming units (CFU) on blood agar at baseline and after 21 days. The statistical analysis was done by indepentent t-test. Result: The results showed that CFU& PI in group I were significantly reduced when compared to group I with, p Conclusion: Tempered chlorhexidine is a better alternative as an anti-plaque subgingival irrigant and can be preferred over cold chlorhexidine at 0.2% concentration. Keywords: Anti- plaque agents, Biofilm, Chlorhexidine digluconate.

A randomised clinical trial to determine the effect of a toothpaste containing enzymes and proteins on gum health over 3 months

ObjectivesThis study tested the efficacy of a toothpaste containing enzymes and proteins reflecting those naturally occurring in saliva which play an important role in maintaining bacterial balance to improve gingival health condition and reduce supra-gingival plaque formation over a period of 13 weeks as compared to a commercial control toothpaste. MethodsThis study was a double-blind, randomised, parallel group, 3 month home use study in healthy volunteers. Non-smokers with a mean modified gingival index (MGI) score of between 2.00–2.75 and at least 20 natural teeth, a minimum of 5 teeth in each quadrant were enrolled in the study. At screening, participants underwent a dental prophylaxis and were issued with a standard fluoride toothpaste and toothbrush to use for 4 weeks. After 4 weeks, participants demonstrating ongoing eligibility were assessed for gingival health and plaque score and randomised to either test or control toothpaste, which they used at home twice daily. After 13 weeks, gingival health and plaque were re-scored. Results229 participants completed the study. There were no treatment associated adverse events. Plaque and gingival scores were significantly better in the test group as compared to the control group. Furthermore, in the test group plaque and gingival scores fell, while those in the control group rose over the 13 week period. ConclusionsThe test toothpaste containing enzymes and proteins demonstrated significant plaque and gingival benefit compared to the control toothpaste, and was well tolerated. Clinical significanceToothbrushing with the test product derived from naturally occurring enzymes and proteins had a clinical adjunctive improvement on gingival health compared to brushing alone with a commercially available fluoride toothpaste.

Characterisation of a sucrose-independent in vitro biofilm model of supragingival plaque.

Sugar consumption has been decreasing in Japan, suggesting higher rates of sucrose-independent supragingival plaque formation. For developing an in vitro biofilm model of sucrose-independent supragingival plaque, this study aimed to investigate the compositions and functions on contributing to cariogenicity in comparison with sucrose-dependent biofilm. An in vitro multispecies biofilm containing Actinomyces naeslundii, Streptococcus gordonii, S.mutans, Veillonella parvula and Fusobacterium nucleatum was formed on 24-well plates in the absence or presence of 1% sucrose. Compositions were assessed by plate culture, scanning electron microscopy and confocal laser scanning microscopy after fluorescent in situ hybridisation or labelling of extracellular polymeric substances (EPS). Functions were assessed by acidogenicity, adherence strength and sensitivities to anticaries agents. Although both biofilms exhibited a Streptococcus predominant bacterial composition, there were differences in bacterial and EPS compositions; in particular, little glucan EPS was observed in sucrose-independent biofilm. Compared with sucrose-dependent biofilm, acidogenicity, adherence strength and antimicrobial resistance of sucrose-independent biofilm were only slightly lower. However, dextranase degradation was substantially lower in sucrose-independent biofilm. Our findings suggest that sucrose-independent biofilm may have cariogenicity as with sucrose-dependent biofilm. These in vitro models can help further elucidate plaque-induced caries aetiology and develop new anticaries agents.

A randomized controlled clinical study of the effect of daily intake of Ascophyllum nodosum alga on calculus, plaque, and gingivitis.

The aim of this study is to evaluate, in a randomized controlled cross-over study, the effect of daily intake of the alga Ascophyllum nodosum on supragingival calculus, plaque formation, and gingival health over a 6-month period. Sixty-one adults with moderate to heavy calculus formation since their last yearly recall visit participated. In a randomized order over two 6-month periods, they swallowed two capsules daily, comprising a total of 500 mg dried marine alga powder (Ascophyllum nodosum, ProDen PlaqueOff®) or two negative control tablets. During the study, the participants maintained their regular oral habits. Their teeth were professionally cleaned at the start of each period and after the 6-month registrations. A wash out period of 1 month separated the two 6-month periods. Supragingival calculus (Volpe Manhold), gingivitis (Löe and Silness), gingival bleeding (Ainamo and Bay), and plaque (Quigley-Hein) were registered at screening and at the end of the two periods. Differences in oral health between the test and control periods were analyzed using a paired t test and Wilcoxon signed rank test. Fifty-five participants completed the study. After the alga intake, the mean calculus reduction was 52% compared to the control (p < 0.0001). Fifty-two participants showed less calculus formation in the alga group than in the control group. Plaque (p = 0.008) and gingival bleeding (p = 0.02) were also significantly less in the alga group. However, no significant difference was found between the groups for gingivitis (p = 0.13). The alga intake significantly reduced the formation of supragingival calculus and plaque and occurrence of gingival bleeding. The alga has a systemic effect on oral health. Daily intake of the alga Ascophyllum nodosum as an adjunct to customary oral hygiene showed a major reduction of supragingival calculus formation and reduced plaque formation. In addition, the calculus in the alga group was characterized by a more porous and less solid structure and was easier to remove than the calculus in the control group.

Comparative Evaluation of 0.2 percent Chlorhexidine and Magnetized Water as a Mouth Rinse on Streptococcus mutans in Children.

Chlorhexidine (0.2%) is a ‘Gold Standard’ which is commercially available and effective mouth rinse which inhibits supragingival plaque formation and also reduction in the population of S. mutans after rinsing daily. Lately, it has been proved that the force of magnetism has a great influence on the living organism. Magnetized water has its effect on human body when taken regularly for a considerable period but its use in dentistry is still lacking.AimThis study was done to evaluate antibacterial efficacy and effect of dosage, frequency and duration of commercially available 0.2% chlorhexidine mouth rinse and conventionally prepared magnetized water on colony count of S. mutans.Materials and methodsA total of 50 subjects were selected between the age group of 5 to 12 years. A baseline sample was collected before starting with rinses. Then the subjects were divided in four major groups. Group I was chlorhexidine, group II was subdivided into group IIA and group IIB which were magnetized water groups (24 hours of magnetization) rinsing for 1 minute and 3 minutes respectively and group III was magnetized water (72 hours of magnetization) group rinsing for 3 minutes. The samples were collected and sent to microbiological laboratory for S. mutans count.ResultsThe obtained values of all the groups were subjected to statistical analysis.ConclusionThe reduction of S. mutans count of group III was almost in par with group I.

A streptococcal effector protein that inhibits Porphyromonas gingivalis biofilm development

Dental plaque formation is a developmental process involving cooperation and competition within a diverse microbial community, approximately 70 % of which is composed of an array of streptococci during the early stages of supragingival plaque formation. In this study, 79 cell-free culture supernatants from a variety of oral streptococci were screened to identify extracellular compounds that inhibit biofilm formation by the oral anaerobe Porphyromonas gingivalis strain 381. The majority of the streptococcal supernatants (61 isolates) resulted in lysis of P. gingivalis cells, and some (17 isolates) had no effect on cell viability, growth or biofilm formation. One strain, however, produced a supernatant that abolished biofilm formation without affecting growth rate. Analysis of this activity led to the discovery that a 48&emsp14;kDa protein was responsible for the inhibition. Protein sequence identification and enzyme activity assays identified the effector protein as an arginine deiminase. To identify the mechanism(s) by which this protein inhibits biofilm formation, we began by examining the expression levels of genes encoding fimbrial subunits; surface structures known to be involved in biofilm development. Quantitative RT-PCR analysis revealed that exposure of P. gingivalis cells to this protein for 1&emsp14;h resulted in the downregulation of genes encoding proteins that are the major subunits of two distinct types of thin, single-stranded fimbriae (fimA and mfa1). Furthermore, this downregulation occurred in the absence of arginine deiminase enzymic activity. Hence, our data indicate that P. gingivalis can sense this extracellular protein, produced by an oral streptococcus (Streptococcus intermedius), and respond by downregulating expression of cell-surface appendages required for attachment and biofilm development.

Influence of alcohol in mouthwashes containing triclosan and zinc: an experimental gingivitis study

An experimental gingivitis model was used to analyse the influence of alcohol in mouthwashes containing 0.15% triclosan and zinc chloride on the formation of supragingival plaque, the development of gingivitis and the appearance of adverse events. Using a double-blind crossover design, 30 subjects underwent two consecutive experimental phases with two 0.15% triclosan and zinc chloride mouthwashes, differentiated mainly by their excipient (hydroalcoholic or aqueous). In each phase, the subjects discontinued all oral hygiene measures and were treated solely with the randomly assigned experimental mouthwash for 21 days. Each experimental phase was preceded by a 14-day washout period in which, after receiving a complete oral prophylaxis, the subjects were instructed to perform thorough oral hygiene procedures. Gingivitis and plaque levels were assessed at the start and end of both the experimental phases. The evolution of the gingivitis and plaque indices showed no statistically significant differences between both treatments. The mean gingival index increased from 0.30 to 0.38 with the non-alcoholic mouthwash and from 0.32 to 0.42 with the hydroalcoholic mouthwash. The respective changes in plaque index were from 0.88 to 1.93 and from 0.94 to 1.92. The hydroalcoholic mouthwash produced a larger number of fresh symptoms (p=0.033), oral itching being the most reported. Alcohol does not influence the effectiveness of a 0.15% triclosan and zinc chloride mouthwash against gingivitis development and supragingival plaque formation. The absence of alcohol significantly decreases the incidence of adverse events produced by the mouthwash.

Suppression of angiogenesis by the plant alkaloid, sanguinarine

Sanguinarine is a benzophenanthridine alkaloid derived from the root of Sanguinaria canadensis. Its principal pharmacologic use is in dental products where it has antibacterial, antifungal, and anti-inflammatory activities that reduce gingival inflammation and supragingival plaque formation. Angiogenesis is indispensable for inflammation, and most angiogenesis is dependent on vascular endothelial growth factor (VEGF). However, the effect of sanguinarine on angiogenesis is not known. In the present study, we examined the effect of sanguinarine on VEGF-induced angiogenesis in vitro and in vivo. Interestingly, sanguinarine markedly suppressed VEGF-induced endothelial cell migration, sprouting, and survival in vitro in a dose-dependent manner at nanomolar concentrations. Furthermore, sanguinarine potently suppressed blood vessel formation in vivo in mouse Matrigel plugs and the chorioallantoic membrane of chick embryos. Our biochemical assays indicated that sanguinarine strongly suppressed basal and VEGF-induced Akt phosphorylation, while it did not produce any changes in VEGF-induced activation of ERK1/2 and PLCγ1. Therefore, we conclude that sanguinarine is a potent antiangiogenic natural product, and its mode of action could involve the blocking of VEGF-induced Akt activation. Thus, in addition to antibacterial, antifungal, and anti-inflammatory activities, sanguinarine has a novel antiangiogenic role.

Impact of mouthrinses on morning bad breath in healthy subjects

During sleep, a proliferation of oral bacteria is responsible for the release of offending gases in morning breath even in healthy people. Thus, the aim of this study was to evaluate the bad breath-inhibiting effect of four commercially available mouthrinses (0.03% triclosan, 0.12% chlorhexidine gluconate, 0.05% cetylpyridinium chloride and essential oils) on morning breath when compared with a positive and a negative control. A six-step double-blind, crossover, randomised study was conducted in 12 dental students with healthy periodontium, who refrained from mechanical plaque control during a 4-day period. The subjects were instructed to rinse twice daily with the assigned product during each period. Fifteen-day washout intervals were used. Before professional plaque and tongue coating removal (baseline), the morning breath was scored through volatile sulphur compounds (VSCs) level measured by a sulphide monitor. After 4 days, VSCs and plaque index (PI) were recorded. Even in the absence of mechanical plaque control, there was a decrease in VSC level with the use of all mouthrinses, with the exception of an increase with the use of the negative control. The VSC formation was inhibited in descending order, by positive control (0.2% chlorhexidine), 0.12% chlorhexidine, triclosan and essential oils and cetylpyridinium chloride. Plaque formation was inhibited by chlorhexidine mouthrinses and essential oils. These findings suggest that mouthrinses can reduce morning bad breath, and that such a reduction is not attributable only to the reduction of supragingival plaque formation.

Actinomyces spp. in Supragingival Plaque of Ethnic Chinese Preschool Children with and without Active Dental Caries

Very limited molecular epidemiological data are available on the role of Actinomyces spp. in the pathogenesis of caries in the primary dentition. Therefore, we investigated their distribution in supragingival plaque of ethnic Chinese preschool children from Singapore and Hong Kong, either with or without active caries. Plaque samples were taken from intact interproximal enamel areas using dental floss. Bacterial genomic DNA of each sample was extracted and variable regions of 16S ribosomal DNA amplified and labelled with digoxigenin. Oligonucleotide probes specific for Actinomyces bovis, Actinomyces gerencseriae, Actinomyces israelii, Actinomyces meyeri, Actinomyces odontolyticus, catalase-negative Actinomyces naeslundii (genospecies 1 and 2) and catalase-positive Actinomyces naeslundii genospecies 2 (previously Actinomyces viscosus serotype II) were used to detect these species using Southern hybridization with a Minislot and Miniblotter system. A. odontolyticus, A. gerencseriae and A. meyeri were detected with similar frequency in both Singapore and Hong Kong samples or in those with and without active caries. However, the prevalence of A. naeslundii was significantly different in the two locales (p < 0.05). A. odontolyticus (88.7%), A. gerencseriae (56.6%) and A. naeslundii (50.9%) were detected in a majority of the samples and the positive hybridization signals of A. gerencseriae in the caries-active group were stronger than from the caries-free group. A. bovis and A. israelii were undetectable in any of the samples. These data imply that A. odontolyticus, A. naeslundii and A. gerencseriae may play an important role in supragingival plaque formation on primary teeth in ethnic Chinese, with others such as A. meyeri contributing.

Effect of a Mouthrinse Containing Selected Propolis on 3-Day Dental Plaque Accumulation and Polysaccharide Formation

The aim of this study was to evaluate the effect of a mouthrinse containing propolis SNB-RS on 3-day dental plaque accumulation. Six volunteers took part in a double-blind crossover study performed in two phases of 3 days. During each phase the volunteers refrained from all oral hygiene and rinsed with 20% sucrose solution 5 times a day to enhance dental plaque formation and with mouthrinse (placebo or experimental) twice a day. On the 4th day, the plaque index (PI) of the volunteers was scored and the supragingival dental plaque was analyzed for insoluble polysaccharide (IP). The PI (SD) for the experimental group was 0.78 (0.17), significantly less than for the placebo group, 1.41 (0.14). The experimental mouthrinse reduced the IP concentration in dental plaque by 61.7% compared to placebo (p < 0.05). An experimental mouthrinse containing propolis SNB-RS was thus efficient in reducing supragingival plaque formation and IP formation under conditions of high plaque accumulation.

Atomic Force Microscopic Study of Commercially Available Implant Abutments

Clinical studies have reported a correlation between the surface roughness of implant abutments and the rate of supragingival and subgingival plaque formation. In order to maintain periimplant health, it is important to understand the relationship between abutment surface characteristics and plaque formation. The aim of this study was to use high image resolution imaging techniques for analysis of implant abutment surface topography. Five commercially available implant abutments (Brånemark, Nobel Biocide, AB, Goteborg, Sweden, Astra, Astra Tech AB, Mondal, Sweden, IMZ, Friatec AG, Mannheim, Germany, Steri-Oss, Denar Corp, Anaheim, Calif, USA, and POI, Kyocera Corp, Kyoto, Japan) were visually and quantitatively characterized using an atomic force microscope. Statistical analysis by analysis of variance and Fishers's Protected Least Significant Differences showed significant differences (p < .05) between arithmetic mean deviation values of surface relative to the center plane (Sa). Power spectral density analysis also was effective as a spacing parameter. Sectional profiles measured the exact length, depth, or height of the specific features on the images. Within the limits of this study, the Brånemark, Astra and IMZ abutments displayed turning marks in x direction from the procedure. The Steri-Oss abutment showed smoothest surface among the five abutments tested.

Microbial generation time during the early phases of supragingival dental plaque formation.

The objective of this investigation was to determine the microbial generation time during early human supragingival plaque formation. On 2 occasions, 13 participants refrained from all oral hygiene measures for periods of 1, 2, 4, 8, 24 and 72 h. Plaque was sampled from defined areas of the teeth 13, 14, 15, 23, 24 and 25. Two independent methods were used to estimate the total number of viable cells: colony-forming units BCVF, total bacterial counts (BC) as enumerated by microscopic examination, and the percentage of vital bacteria using a vital fluorescence technique (VF) were recorded. The total number of vital microorganisms was calculated by BCVF (= BC x VF). The generation time based on either colony-forming units or BCVF increased significantly with plaque age. During the first interval (1-4 h), the microbial multiplication took slightly less than 1 h. After the establishment of a more mature plaque (24-72 h), the replicating time was between 12.5 h (BCVF) and 14.8 h (colony-forming units). It was concluded that the microbial generation time recorded at the initial stages of plaque formation is considerably lower than that found in older plaque.

Reduction of Plaque Formation and Gingivitis by a Dentifrice Containing Triclosan and Copolymer

A 6-month, single-blind and parallel clinical study was conducted to compare the effects of dentifrice containing 0.3% triclosan and 2.0% of copolymer (methoxyethylene and maleic acid) with a customary oral hygiene procedure on supragingival plaque formation and gingivitis. The 124 subjects were stratified into two balanced groups on the basis of their baseline plaque and gingivitis scores. After complete oral prophylaxis, subjects were assigned to use either a triclosan/copolymer dentifrice or to practice their customary oral hygiene care for 6 months. Plaque formation and gingivitis were scored at 3 and 6 months. After 3 and 6 months, triclosan/copolymer produced 7.17% and 12.07% significantly greater reduction of plaque formation than the customary oral hygiene group, respectively. Triclosan/copolymer significantly reduced gingivitis by 5.20% at 3 months, while no significant differences between the two groups were observed at 6 months. Likewise, triclosan/copolymer provided 8.70% and 16.33% significantly greater reduction of plaque severity index at 3- and 6-month evaluation, respectively. Gingivitis severity index was significantly reduced by 25% at 3 months, but there were no differences between the two groups at 6 months. These results indicate that the triclosan/copolymer dentifrice was better than the customary oral hygiene care in preventing supragingival plaque formation up to 6 months and in reducing gingivitis up to 3 months.

The influence of surface roughness and surface-free energy on supra- and subgingival plaque formation in man. A review of the literature.

In the oral cavity, an open growth system, bacterial adhesion to the non-shedding surfaces is for most bacteria the only way to survive. This adhesion occurs in 4 phases: the transport of the bacterium to the surface, the initial adhesion with a reversible and irreversible stage, the attachment by specific interactions, and finally the colonization in order to form a biofilm. Different hard surfaces are available in the oral cavity (teeth, filling materials, dental implants, or prostheses), all with different surface characteristics. In a healthy situation, a dynamic equilibrium exists on these surfaces between the forces of retention and those of removal. However, an increased bacterial accumulation often results in a shift toward disease. 2 mechanisms favour the retention of dental plaque: adhesion and stagnation. The aim of this review is to examine the influence of the surface roughness and the surface free energy in the adhesion process. Both in vitro and in vivo studies underline the importance of both variables in supragingival plaque formation. Rough surfaces will promote plaque formation and maturation, and high-energy surfaces are known to collect more plaque, to bind the plaque more strongly and to select specific bacteria. Although both variables interact with each other, the influence of surface roughness overrules that of the surface free energy. For the subgingival environment, with more facilities for microorganisms to survive, the importance of surface characteristics dramatically decreases. However, the influence of surface roughness and surface-free energy on supragingival plaque justifies the demand for smooth surfaces with a low surface-free energy in order to minimise plaque formation, thereby reducing the occurrence of caries and periodontitis.

Clinical relevance of the influence of surface free energy and roughness on the supragingival and subgingival plaque formation in man

Previous clinical studies illustrated a positive correlation between the rate of “supragingival” plaque maturation and both the free energy and roughness of the intraoral hard surfaces (teeth, prostheses, implants). The present review of the literature aims to examine the clinical importance of these parameters especially in the “subgingival” environment, where plaque causes periodontitis. Despite the clear cut differences between supragingival and subgingival environments (with more possibilities for adhesion and fewer removal forces for the latter), both the surface roughness and the surface free energy remain important. This could be proven in an in vivo study in patients with implant-supported prostheses, where abutments (trans-mucosal connections between implant in the bone and prosthetic reconstruction) with different surface characteristics were examined. After an undisturbed subgingival plaque formation of 3 months, the roughened surfaces harboured significantly more bacteria (51 × 10 4 colony-forming units (CFU)) than both smooth abutments (3 × 10 4 CFU), and fluorinated ethylene-propylene (FEP) coated abutments with comparable roughness (11 × 10 4 CFU). The plaque composition was also slightly surface dependent, with a more pathogenic situation around the roughened titanium abutments. However, if the “in the pocket swimming flora” was considered, most differences disappeared.

Scanning electron microscopic observations of early plaque formation in vivo on enamel specimens treated with delmopinol

The aim of this double blind, cross-over, scanning electron microscopic (SEM) study was to compare the effect of topical application of 0.5% delmopinol HCl (aqueous solution) with placebo on early supragingival plaque formation on enamel specimens attached to a maxillary premolar. 3 subjects underwent 2x (placebo and delmopinol treatment, respectively) 7 treatment periods (1/2, 1, 2, 8, 24 hours; 3, 7 days) of undisturbed dental plaque accumulation, during which 2 ml of placebo and delmopinol HCl 0.5%, respectively, were applied topically to all teeth 2x daily. At the end of each period, the specimen was retrieved and processed for SEM. For the specimens obtained after 24 h or less, the number of visible micro-organisms was estimated. For the 3- and 7-day specimens, the area covered by plaque was calculated planimetrically. Large inter-individual differences were observed in the number of bacteria attaching during the first 24 h, with apparently no major differences between delmopinol and placebo. 1 subject showed a bacterial colonization predominated by curved rods throughout the first 8 h. Compared to placebo, the area of the specimens covered by plaque was reduced after 3 and 7 days of delmopinol use, with coccoid cells as the predominant morphotype. Plaque maturity, characterized by the appearance of corncob formations and high numbers of different morphotypes, was not observed on the delmopinol specimens, in contrast to the placebo specimens. The study shows that topical application of 0.5% delmopinol HCl delays and interferes with dental plaque maturation.

Comparison of the distribution of Actinomyces in dental plaque on inserted enamel and natural tooth surfaces in periodontal health and disease

The distribution of Actinomyces naeslundii, Actinomyces viscosus and Actinomyces odontolyticus in healthy and diseased adult populations was studied in 3 different ways. First, supragingival plaque formation at 2 through 72 h was examined in 12 periodontally healthy adults using a removable pre-measured surface of enamel bonded to molars and premolars. Second, a cross-sectional examination of the composition of both supragingival and subgingival plaque of unknown age was conducted in 205 adults exhibiting periodontal health to moderate disease. Third, the effects of oral hygiene instruction and root planing on the subgingival microflora of a subset of 19 subjects with moderate periodontitis were examined. The evaluation of 12 adults revealed that the predominant species in early plaque formation (2, 4 and 8 h) was A. odontolyticus. A. viscosus and A. naeslundii were present in developing plaques in almost all subjects in 2-h plaque, but absent in half the subjects when 4-, 8- or 24-h plaque was examined. These two species significantly increased in numbers per mm2 enamel surface area in 48- and 72-h plaques. A. odontolyticus was not related to clinical signs of periodontal disease in 205 adults, and its subgingival proportions in plaque did not change following periodontal treatment of 19 individuals. A. naeslundii was found in significantly higher numbers in supragingival than subgingival plaques in the 205 adults examined. The mean proportion of A. naeslundii significantly decreased as the magnitude of probing depth and attachment loss increased. The proportions of A. naeslundii and A. viscosus were found to be significantly increased in subgingival plaques following periodontal treatment.

Microbiology of early supragingival plaque development after delmopinol treatment

The aim of this double blind, cross-over, microbiological study was to compare the effect of topical application of the plaque control agent 0.5% delmopinol HCl with placebo on early supragingival plaque formation. Six subjects underwent 7 periods (0.5, 1, 2, 8 and 24 h and 3 and 7 days) of placebo and delmopinol application, respectively. At the start of each study period the teeth were professionally cleaned and 2 ml of placebo and delmopinol 0.5%, respectively, were applied on all teeth (twice daily for periods lasting 24 h or more). At the end of each period, supragingival plaque samples of one upper and one lower buccal tooth surface were collected separately and cultured on anaerobically incubated Brucella blood agar, on aerobically incubated blood agar and on selective media for the enumeration of Streptococcus spp., Haemophilus spp., Actinomyces spp., Veillonella spp., Neisseria spp. and Fusobacterium spp. The total anaerobic cultivable microflora after delmopinol use was 10-100 times lower than after placebo use. Compared with placebo, the proportion of cultivable aerobes (61.3%), Streptococcus spp. (104.8%) and Haemophilus spp. (82.3%) increased and the proportion of Actinomyces spp. (86.1%), Veillonella spp. (60.5%), Neisseria spp. (96.9%) and Fusobacterium spp. (60.6%) decreased after 7 days. Short-term application of 0.5% delmopinol HCl on supragingival dental plaque regrowth resulted in a reduction of the number of cultivable microorganisms in the plaque and produced a shift in the cultivable plaque composition.