Mechanisms of dental plaque formation

The anti-plaque effect of high concentration sodium bicarbonate dentifrice on plaque formation and gingival inflammation, irrespective to individual polishing technique and plaque quality

AIM

To assess the anti-plaque effect of a high concentration sodium bicarbonate dentifrice on plaque formation, and gingivitis, as compared to a control toothpaste, irrespective of individual brushing technique and plaque quality.

METHODS

The experimental gingivitis model, with a split-mouth design was used to assess the anti-plaque effect of a high concentration sodium bicarbonate dentifrice on plaque formation. By producing individual fitted trays, the toothpaste was applied in the test quadrant and a control dentifrice in the contralateral. The participants used the individual fitted trays for 1 min every morning and evening, for 21 days. In this period, the participants was only allowed to brush the teeth in the opposite jaw, as usual. Twenty healthy individuals successfully completed the study.

RESULTS

At 21 days, there was no statistically significant difference between test quadrant and control quadrant with regard to plaque indices, gingival index and number of bleeding sites.

CONCLUSION

This study demonstrated that the high concentration sodium bicarbonate dentifrice used did not produce statistically significant anti-plaque effect compared to the control dentifrice, in terms of Plaque- and Gingival Indices, number of bleeding sites or by Quigely and Hein, the Turesky modification Plaque Index, irrespective of brushing technique and individual plaque quality.

TRIAL REGISTRATION

Regional Committee for Medical Research and Ethics, South-East Norway in 2021 (REK.2021/370116).

CLINICAL TRIAL REGISTRATION

NCT05441371 (First registered 09/06/2022, First posted 01/07/2022) ( http://www.

CLINICALTRIALS

gov ). (Retrospectively registered).

The influence of fixed prosthesis placement on the clinical effectiveness of non-surgical periodontal therapy

Background/purpose

Fixed prostheses are essential for restoring teeth with compromised structures. However, the margins of prosthesis potentially create an interface that interferes with proper cleaning. This study evaluated whether the fixed prosthesis placement influenced the clinical effectiveness of non-surgical periodontal therapy (NSPT).

Materials and methods

Clinical records from 202 patients with generalized chronic periodontitis receiving NSPT at the National Taiwan University Hospital in 2012-2014 were included. The change and improvement ratio (IR) of clinical parameters following NSPT in the entire dentition or posterior region, and all or periodontitis-affected teeth/crowns (T/C) and sites were evaluated. The differences among natural teeth (NT), prosthetic crowns (PC), and abutments (AB) were compared by using Kruskal-Wallis tests followed by Dunn's post-hoc test.

Results

Gingival recession (REC) was greater in PC and AB groups than in the NT group before NSPT, while tooth mobility was also lower in the AB group. REC gain was lower in the AB group after NSPT, while mobility reduction was inferior in the PC and AB groups for all or periodontitis-affected T/C and sites. In periodontitis-affected T/C, IRs in probing pocket depth reduction and clinical attachment gain were lower in the PC group, and mobility reduction was lower in the AB group. The tendency in the posterior region is similar but was less pronounced than in the entire dentition.

Conclusion

The effectiveness of NSPT and the improvement of periodontal parameters are reduced when fixed prostheses present. MB reduction is inferior in AB teeth relative to NT.

Bacterial Growth on Three Non-Resorbable Polytetrafluoroethylene (PTFE) Membranes-An In Vitro Study

GBR (Guided Bone Regeneration) procedure is challenged by the risk of membrane exposure to the oral cavity and contamination. The barrier quality of these membranes serve as a mechanical block from bacterial penetration into the GBR site. The purpose of this in vitro study was to evaluate the antibacterial effect of three commercial non-resorbable polytetrafluoroethylene membranes. (Two d-PTFE membranes and one double layer e-PTFE +d-PTFE membrane). A validated in vitro model with two bacterial species (Streptococcus sanguinis and Fusobacterium nucleatum) was used. Eight samples from membrane each were placed in a 96-well microtiter plate. The experimental and positive control groups were exposed to a bacterial suspension which involved one bacterial species in each plate. Bacterial growth was monitored spectrophotometrically at 650 nm for 24 h in temperature controlled microplate spectrophotometer under anaerobic conditions. One- Sample Kolmogorov−Smirnov Normal test and the Kruskal−Wallis test was used for the statistical analysis. As shown by the bacterial growth curves obtained from the spectrophotometer readings, all three membranes resulted in bacterial growth. We have not found a statistical difference in F. nucleatum growth between different membrane samples and the positive control group. However, S. sanguinis growth was reduced significantly in the presence of two membranes (CYTOPLAST TXT-200 and NeoGenTM) when compared to the control (p < 0.01). The presence of Permamem® had no significant influence on S. sanguinis growth. Some types of commercial non-resorbable PTFE membranes may have an impact on the growth dynamics of specific bacterial species.

Comparative analysis of biofilm formation on materials used for the fabrication of implant supported prostheses

Background:

Zirconia and other dental pottery, heat-restored polymethyl methacrylate, titanium and other metal amalgams, or a mix of these materials are utilized to fix inserts. It is important to choose a material that is resistant to bacterial colonization for implant-supported prostheses, but durability and aesthetics are important factors as well.

Aim:

Biofilm generation on materials used in implant-supported dental prosthesis manufacturing was an objective of this investigation.

Methods and Materials:

In this study, 90 discs were prepared. These discs were divided into three groups: group PMMA, group Y-TZP, and group CP-Ti. Each group consisted of 30 discs. As helpful materials, 30 discs (D = 15 mm, H = 3 mm) each were created from either monetarily unadulterated titanium (CP-Ti), yttria tetragonal zirconia polycrystal (YTZP), or hotness-restored polymethyl methacrylate (PMMA). The examples were cleaned as per acknowledged practices. The non-contact profilometer (NPFLEX, Bruker, UK) was utilized to survey the surface rougness of each disc, and the outcomes were accounted for as Ra (m). An assortment of gram-negative microbes, including Aggregatibacter actinomycetemcomitans, Tannerella forsythia, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella albicans, were refined close by cleaned discs produced using heat-relieved PMMA, Y-TZP, or CP-Ti to see which type of biofilm is shaped best. CFU/mL was the unit of estimation (state framing units per milliliter).

Results:

Y-TZP discs have a substantially higher Ra (349 41 m) than PMMA and CP-Ti discs. Some bacteria that have been associated with peri-mucositis and peri-implantitis may be less prevalent on Y-TZP or CP-Ti discs. Biofilm development must be considered while making implant-supported prostheses using Y-TZP and CP-Ti.

Conclusion:

Y-TZP and CP-Ti are preferred materials for implant-supported prosthesis production because of biofilm development.

A review on natural teeth whitening

BACKGROUND

Discoloration of teeth occurs for various reasons. Common ingredients like substances from tea and coffee, as well as antibiotics like tetracycline, or food dyes, can percolate into the teeth, and, as such, these stains may persist in the porous structure of the enamel. Smoking is also contributory to dental discoloration, with toxins of tobacco smoke accumulating in a similar way. With aging, teeth tend to be discolored with accumulation of various stains in addition to the enamel gradually eroding to expose the yellow dentin.

HIGHLIGHT

This review focused on the effect of several natural ingredients with teeth-whitening properties and their daily clinical application. Metabolic dental bleaching mechanisms, as well as tooth discoloration and decay, were also reviewed. The current scientific literature (mostly from 2000 to 2020) was consolidated from manuscripts retrieved from Scopus, PubMed, ResearchGate, and Google Scholar.

CONCLUSION

Natural teeth whitening effectively lightens the natural color of teeth without eroding dental surfaces. On the other hand, commercially available whiteners containing hydrogen peroxide and carbamide peroxide, in high concentrations, can lead to deproteinization and demineralization of teeth through oxidation processes. If used extensively, these compounds may cause a number of adverse effects. Alternative natural teeth-whiteners include ingredients like lemons, strawberries, oranges, papaya, and other fruits. Such natural ingredients offer a milder and safer way of whitening teeth than whiteners containing hydrogen peroxide or carbamide peroxide.

Antibacterial effects of saliva substitutes containing lysozyme or lactoferrin against Streptococcus mutans

OBJECTIVE

To determine the antibacterial effects of different saliva-substitutes-containing-lysozyme(LYZ) or-lactoferrin(LF) on Streptococcus mutans(S. mutans) in comparison with human saliva.

DESIGN

In vitro wound-healing assay was performed with L929 mouse fibroblast cell line by using various concentrations of LYZ and LF to determine optimum concentrations and to confirm do not show any cytotoxicity of proteins according to cell culture studies. Antibacterial effect was assessed by determining Minimum Inhibitory Concentrations for all groups on S.mutans. Bacterial adhesion of S. mutans for 4 h on hydroxyapatite(HAP) discs after application of different saliva substitutes was evaluated. The formulations were:saliva-substitute(Group SS);saliva-substitute-containing-Lactoferrin(Group SSLF);saliva-substitute-containing-Lysozyme(Group SSLYZ). Human saliva was control group(Group HS).

RESULTS

In vitro wound healing assay results showed that, when added into the cell culture media, LYZ and LF significantly increase 48 -h scratch wound closure compared to the cell culture media(p < 0.0001). At the end of second day, samples treated with both between 2.5-100 μg/mL LF and 5-200 μg/mL LYZ were found to have significant wound healing effect(p < 001). It was observed that saliva-substitutes-containing-LYZ or-LF had antibacterial effects on S.mutans. Bacterial adhesion on HAP discs was observed significantly higher in control group than in study groups. The amount of adhered S. mutans was significantly higher in Group SS than other study groups(p < 0.0001). However, no statistically significant difference was found between the number of bacteria adhered to HAP discs between SSLYZ and SSLF groups(p > 0.05).

CONCLUSIONS

The study of cell viability and wound healing was great significance in the optimum concentrations of LYZ and LF. Among formulations, saliva-substitutes-containing-LYZ or-LF exhibited higher inhibitory effect on S.mutans.

Effects of Initially Adsorbed Proteins on Substrate Surfaces during Multilayer Heterogeneous Protein Adsorption

When multilayer heterogeneous proteins are adsorbed on substrate surfaces, the effects of the adsorption state of the initially adsorbed proteins may affect subsequent adsorption. In this study, the relationships between the adsorption state of the initially adsorbed proteins and the amount of secondary adsorbed proteins were examined. A carboxylate-terminated self-assembled monolayer was applied to bovine serum albumin (BSA) solutions of different concentrations for 180 min and subsequently applied to phosphate-buffered saline (PBS) for an additional 180 min to remove weakly adsorbed proteins. The amount of adsorbed proteins was measured using a quartz crystal microbalance with dissipation. The obtained BSA adsorption layer was then applied to mucin solution for 60 min. When a 1.7 mg/mL BSA solution was applied to the surface, the amount of adsorbed BSA after 10 min of adsorption and after washing with PBS for 167 min was >5 × 10² ng/cm², representing the saturation amount of monolayer-adsorbed BSA in a side-on orientation. In contrast, the amount of adsorbed BSA after 10 min adsorption was <5 × 10² ng/cm² when a BSA solution with a concentration <0.43 mg/mL was used. The velocity of BSA adsorption plateaued at approximately 0.43 mg/mL, suggesting that the orientation of the adsorbed protein was determined by protein treatment concentration immediately after the proteins were adsorbed. Furthermore, the amount of adsorbed mucin on the BSA adsorption layer decreased as initial BSA treatment concentration increased up to 0.43 mg/mL and plateaued at concentrations above 0.43 mg/mL. These results indicated that the orientation of the initially adsorbed protein was preserved for several hours and affected the subsequent adsorption of mucin.

Oral care product formulations, properties and challenges

This review explores the physical, chemical and structural properties of key components of oral care products, whilst looking at the challenges which need to be overcome to continue to improve the efficacy of oral care, and improve dental health. Oral care has been an essential part of all populations and cultures around the world for thousands of years. To maintain good oral health, dental plaque causing bacteria and malodour must be controlled whilst also strengthening and protecting the teeth to prevent dental caries. Advanced modern formulations need to provide controlled and extended release of ingredients vital for dental health. With modern day products such as toothpastes and mouthwashes, it has never been easier to maintain good oral hygiene and health, yet the incidence of dental caries is still on the rise. The complex formulations of modern toothpastes and mouthwashes makes them one of the most sophisticated pharmaceutical products on the market today. The demands of the consumer coupled with the complexity of the oral cavity make it one of the most challenging development processes.

Comparative Analysis of Biofilm Formation on Materials Used for the Fabrication of Implant-Supported Prostheses

The purpose of this study was to compare biofilm formation on materials used for the fabrication of implant-supported dental prostheses. Twenty discs (D=15 mm, H=3 mm) were fabricated from one of the following restorative materials: yttria tetragonal zirconia polycrystal (Y-TZP); commercially pure titanium (CP-Ti); or heat-cured polymethyl methacrylate (PMMA). Specimens were polished following standard protocols. A non-contact profilometer (NPFLEX, Bruker, UK) was used to assess the surface roughness of each disk; results were reported as Ra (µm). Five strains of Gram-negative bacteria frequently associated with peri-implantitis, Aggregatibacter actinomycetemcomitans, Candida. albicans, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia, were cultured on hand-polished discs fabricated from heat-cured PMMA, Y-TZP, or CP-Ti to compare biofilm formation on each type of material. The results were reported as colony-forming units per milliliter (CFU/mL). One-way ANOVA and post hoc tests were used to compare surface roughness and bacterial colonization on the respective materials. Statistical significance was set at a = 0.05. Discs fabricated from Y-TZP had a significantly higher Ra value (350 ± 30 µm) than either PMMA, or CP-Ti discs. Discs fabricated from either Y-TZP and CP-Ti may exhibit less colonization by bacteria associated with peri-mucositis and peri-implantitis. Y-TZP and CP-Ti are suggested materials for fabrication of implant-supported prostheses, considering biofilm formation.

Effect of Er:YAG laser irradiation on deciduous enamel roughness and bacterial adhesion: An in vitro study

Laser irradiation has been proposed as a preventive method against dental caries since it is capable to inhibit enamel demineralization by reducing carbonate and modifying organic matter, yet it can produce significant morphological changes. The purpose of this study was to evaluate the influence of Er:YAG laser irradiation on superficial roughness of deciduous dental enamel and bacterial adhesion. Fifty-four samples of deciduous enamel were divided into three groups (n = 18 each). G1_control (nonirradiated); G2_100 (7.5 J/cm² ) and G3_100 (12.7 J/cm² ) were irradiated with Er:YAG laser at 7.5 and 12.7 J/cm² , respectively, under water irrigation. Surface roughness was measured before and after irradiation using a profilometer. Afterwards, six samples per group were used to measure bacterial growth by XTT cell viability assay. Adhered bacteria were observed using confocal laser scanning microscopy (CLSM) and a scanning electron microscopy (SEM). Paired t-, one-way analysis of variance (ANOVA), Kruskal-Wallis and pairwise Mann-Whitney U tests were performed to analyze statistical differences (p < .05). Before treatment, samples showed homogenous surface roughness, and after Er:YAG laser irradiation, the surfaces showed a significant increase in roughness values (p < .05). G3_100 (12.7 J/cm² ) showed the highest amount of Streptococcus mutans adhered (p < .05). The increase in the roughness of the tooth enamel surfaces was proportional to the energy density used; the increase in surface roughness caused by laser irradiation did not augment the adhesion of Streptococcus sanguinis; only the use of the energy density of 12.7 J/cm² favored significantly the adhesion of S. mutans.

Biofilms and their properties

Bacteria within the oral cavity live primarily as complex, polymicrobial biofilms. Dental biofilms are necessary etiological factors for dental caries and periodontal diseases but have also been implicated in diseases outside the oral cavity. Biofilm is the preferred lifestyle for bacteria, and biofilms are found on almost any surface in nature. Bacteria growing within a biofilm exhibit an altered phenotype. Substantial changes in gene expression occur when bacteria are in close proximity or physical contact with one another or with the host. This may facilitate nutritional co-operation, cell-cell signaling, and gene transfer, including transfer of antibiotic-resistance genes, thus rendering biofilm bacteria with properties other than those found in free-floating, planktonic bacteria. We will discuss biofilm properties and possible consequences for future prophylaxis.

In vitro aging behavior of dental composites considering the influence of filler content, storage media and incubation time

Objective

Over time dental composites age due to mechanical impacts such as chewing and chemical impacts such as saliva enzymes and food ingredients. For this research, the focus was placed on chemical degradation. The objective of this study was to simulate hydrolysis by using different food simulating liquids and to assess their impact on the mechanical parameter Vickers microhardness (MHV) and the physicochemical parameter contact angle (CA).

Methods

Specimen of three composites (d = 6 mm, h = 2 mm; n = 435) classified with respect to their filler content (wt%), namely low-filled, medium-filled and highly-filled, were stored for 0, 14, 30, 90 and 180 days in artificial saliva (pH 7), citric acid (pH 3; pH 5), lactic acid (pH 3; pH 5) and ethanol (40%vol; 60%vol) and assessed regarding to MHV and CA. Statistics: Kruskal-Wallis test, stepwise linear regression, bivariate Spearman Rank Correlation (p < 0.05).

Results

While stored in artificial saliva, acid and ethanol the CA decreased especially for the low- and medium-filled composites. It was shown that rising the filler content caused less surface changes in the CA. Storage in ethanol led to a significant decrease of MHV of all composites. Regression analysis showed that the effect of in vitro aging on MHV was mainly influenced by the composite material and therefore by filler content (R² = 0.67; p < 0.05). In contrast, the CA is more influenced by incubation time and filler content (R² = 0.2; p < 0.05) leading to a higher risk of plaque accumulation over time. Significance: In vitro aging showed significant changes on the mechanical and physicochemical properties of dental composites which may shorten their long-term functionality. In conclusion, it can be stated, that the type of composite material, especially rising filler content seems to improve the materials’ resistance against the processes of chemical degradation.

Which orthodontic appliance is best for oral hygiene? A randomized clinical trial

INTRODUCTION

Clear aligners and to a lesser extent self-ligated brackets are considered to facilitate better oral hygiene than traditional fixed orthodontic appliances. This 3-arm parallel-group prospective randomized clinical trial compared the long-term and short-term effects of clear aligners, self-ligated brackets, and conventional (elastomeric-ligated) brackets on patients' oral hygiene during active orthodontic treatment.

METHODS

Seventy-one participants (41 boys, 30 girls; mean age, 15.6 years) undergoing orthodontic treatment were randomly allocated through a computer-generated randomization schedule to one of the groups based on the choice of intervention: Clear Aligners (CLA) (Align Technology, San Jose, Calif) (n = 27), preadjusted edgewise fixed appliance with self-ligated brackets (SLB) (Carriere, Carlsbad, Calif (n = 22), or preadjusted edgewise fixed appliance with elastomeric ligated brackets (ELB) (Ortho Organizers Inc., Carlsbad, CA) (n = 22). For each participant, the primary outcome, plaque index (PI), and secondary outcomes, gingival Index (GI) and periodontal bleeding index (PBI), were measured at baseline (T0), after 9 months of treatment (T1), and after 18 months of treatment (T2). Blinding of the clinicians and the patients to the intervention was impossible. It was only done for outcome assessment and for the statistician. Ten participants did not receive the allocated intervention for various reasons.

RESULTS

The means and standard deviations of PI at T0 (CLA, 0.50 ± 0.51; SLB, 0.65 ± 0.49; ELB, 0.70 ± 0.73), T1 (CLA, 0.83 ± 0.48; SLB, 1.38 ± 0.72; ELB, 1.32 ± 0.67), and T2 (CLA, 0.92 ± 0.58; SLB, 1.07 ± 0.59; ELB, 1.32 ± 0.67) were similar. The odds ratio (OR) for plaque index (0 or ≥1) comparing SLB or CLA to ELB was not significant. OR for SLB vs ELB = 1.54 at T0 (95% CI, 0.39-6.27), 0.88 at T1 (95% CI, 0.03-24.69), and 0.83 at T2 (95% CI, 0.02-27.70); OR for CLA vs ELB = 1.07 at T0 (95% CI, 0.30-3.88), 0.24 at T1 (95% CI, 0.01-1.98), and 0.17 at T2 (95% CI, 0.01-1.71). However, the odds ratios comparing CLA with ELB for GI (OR = 0.14; P = 0.015) and PBI (OR = 0.10; P = 0.012) were statistically significant at T1.

CONCLUSIONS

In this prospective randomized clinical trial, we found no evidence of differences in oral hygiene levels among clear aligners, self-ligated brackets, and conventional elastomeric ligated brackets after 18 months of active orthodontic treatment.

REGISTRATION

The trial is registered at ClinicalTrials.gov (NCT02745626).

PROTOCOL

The protocol was not published before trial commencement.

Lectins from red algae and their biomedical potential

Lectins are unique proteins or glycoproteins of non-immune origin that bind specifically to carbohydrates. They recognise and interact reversibly to either free carbohydrates or glycoconjugates, without modifying their structure. Lectins are highly diverse and widely distributed in nature and have been extensively reported from various red algae species. Numerous red algae species have been reported to possess lectins having carbohydrate specificity towards complex glycoproteins or high-mannose N-glycans. These lectin-glycan interactions further trigger many biochemical responses which lead to their extensive use as valuable tools in biomedical research. Thus, owing to their exceptional glycan recognition property, red algae lectins are potential candidate for inhibition of various viral diseases. Hence, the present report integrates existing information on the red algae lectins, their carbohydrate specificity, and characteristics of purified lectins. Further, the review also reports the current state of research into their anti-viral activity against various enveloped viruses such as HIV, hepatitis, influenza, encephalitis, coronavirus and herpes simplex virus and other biomedical activities such as anti-cancer, anti-microbial, anti-inflammatory, anti-nociceptive and acaricidal activities.

Antibacterial Peptides: Opportunities for the Prevention and Treatment of Dental Caries

Dental caries is a multifactorial disease that is a growing and costly global health concern. The onset of disease is a consequence of an ecological imbalance within the dental plaque biofilm that favors specific acidogenic and aciduric caries pathogens, namely Streptococcus mutans and Streptococcus sobrinus. It is now recognized by the scientific and medical community that it is neither possible nor desirable to totally eliminate dental plaque. Conversely, the chemical biocides most commonly used for caries prevention and treatment indiscriminately attack all plaque microorganisms. These treatments also suffer from other drawbacks such as bad taste, irritability, and staining. Furthermore, the public demand for safe and natural personal hygiene products continues to rise. Therefore, there are opportunities that exist to develop new strategies for the treatment of this disease. As an alternative to conventional antibiotics, antibacterial peptides have been explored greatly over the last three decades for many different therapeutic uses. There are currently tens of hundreds of antibacterial peptides characterized across the evolutionary spectrum, and among these, many demonstrate physical and/or biological properties that may be suitable for a more targeted approach to the selective control or elimination of putative caries pathogens. Additionally, many peptides, such as nisin, are odorless, colorless, and tasteless and do not cause irritation or staining. This review focuses on antibacterial peptides for their potential role in the treatment and prevention of dental caries and suggests candidates that need to be explored further. Practical considerations for the development of antibacterial peptides as oral treatments are also discussed.

Structural, Surface, in vitro Bacterial Adhesion and Biofilm Formation Analysis of Three Dental Restorative Composites

This study was conducted to investigate the relationship between dental materials and bacterial adhesion on the grounds of their chemical composition and physical properties. Three commercially available dental restorative materials (Filtek™Z350, Filtek™P90 and Spectrum^®TPH^®) were structurally analyzed and their wettability and surface roughness were evaluated by using Fourier Transform Infrared Spectroscopy, Contact Angle Measurement and Atomic Force Microscopy, respectively. These materials were molded into discs and tested with three bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia) for microbial attachment. The bacterial adhesion was observed at different time intervals, i.e., 0 h, 8 h, 24 h, 48 h and 72 h, along with Colony Forming Unit Count and Optical Density measurement of the media. It was found that all materials showed a degree of conversion with time intervals, i.e., 0 h, 8 h, 24 h, 48 h and 72 h, which led to the availability of functional groups (N–H and C–H) that might promote adhesion. The trend in difference in the extent of bacterial adhesion can be related to particle size, chemical composition and surface wettability of the dental materials.

Variation of expression defects in cell surface 190-kDa protein antigen of Streptococcus mutans

Streptococcus mutans, which consists of four serotypes, c, e, f, and k, possesses a 190-kDa cell surface protein antigen (PA) for initial tooth adhesion. We used Western blot analysis to determine PA expression in 750 S. mutans isolates from 150 subjects and found a significantly higher prevalence of the isolates with PA expression defects in serotypes f and k compared to serotypes c and e. Moreover, the defect patterns could be classified into three types; no PA expression on whole bacterial cells and in their supernatant samples (Type N1), PA expression mainly seen in supernatant samples (Type N2), and only low expression of PA in the samples of whole bacterial cells (Type W). The underlying reasons for the defects were mutations in the gene encoding PA as well as in the transcriptional processing of this gene for Type N1, defects in the sortase gene for Type N2, and low mRNA expression of PA for Type W. Since cellular hydrophobicity and phagocytosis susceptibility of the PA-defective isolates were significantly lower than those of the normal expression isolates, the potential implication of such defective isolates in systemic diseases involving bacteremia other than dental caries was suggested. Additionally, multilocus sequence typing was utilized to characterize S. mutans clones that represented a proportion of isolates with PA defects of 65-100%. Therefore, we described the molecular basis for variation defects in PA expression of S. mutans. Furthermore, we also emphasized the strong association between PA expression defects and serotypes f and k as well as the clonal relationships among these isolates.

The effect of surface roughness on ceramics used in dentistry: A review of literature

Long term clinical success of modern dental ceramics depends on a number of factors. These factors include the physical properties of the material, the laboratory fabrication process, the laboratory fabrication technique and clinical procedures that may damage these brittle materials. The surface structure and composition of a dental restorative material influences the initial bacterial adhesion, and a rough material surface will accumulate more plaque. Biomaterials for the restoration of oral function are prone to biofilm formation, affecting oral health. An up to date online database search was performed using the keywords “bacterial biofilm,” “ceramic strength,” “dental ceramics” and “surface roughness.” The searches were performed on Medline/PubMed, and Scopus and the cross references were further searched in the databases to verify further studies. The relevant papers included original articles, systemic reviews, case reports and letters to the editor. All the papers were reviewed, and the most relevant studies were selected for referencing by the author. The aim of this paper is to highlight the influence of rougher surfaces on the ceramic strength and plaque accumulation leading to bacterial biofilm formation.

In vitro efficacy of cold atmospheric pressure plasma on S. sanguinis biofilms in comparison of two test models

Dental plaque critically affects the etiology of caries, periodontitis and periimplantitis. The mechanical removal of plaque can only be performed partially due to limited accessibility. Therefore, plaque still represents one of the major therapeutic challenges. Even though antiseptic mouth rinses reduce the extent of biofilm temporarily, plaque removal remains incomplete and continuous usage can even result in side effects. Here we tested argon plasma produced by kinpen09 as one option to inactivate microorganisms and to eliminate plaque. S. sanguinis biofilms cultivated in either the European Biofilm Reactor (EUREBI) or in 24 well plates were treated with argon plasma. In both test systems a homogeneous, good analyzable and stable biofilm was produced on the surface of titan plates within 72 h (>6,9 log10 CFU/ml). Despite the significantly more powerful biofilm production in EUREBI, the difference of 0.4 log10 CFU/ml between EUREBI and the 24 well plates was practically not relevant. For that reason both test models were equally qualified for the analysis of efficacy of cold atmospheric pressure plasma. We demonstrate a significant reduction of the biofilm compared to the control in both test models. After plasma application of 180 s the biofilm produced in EUREBI or in 24 well plates was decreased by 0.6 log10 CFU/ml or 0.5 log10 CFU/ml, respectively. In comparison to recently published studies analyzing the efficacy of kinpen09, S. sanguinis produces a hardly removable biofilm. Future investigations using reduced distances between plasma source and biofilm, various compositions of plasma and alternative plasma sources will contribute to further optimization of the efficacy against S. sanguinis biofilms.

Anticariogenic and phytochemical evaluation of Eucalyptus globules Labill

In the present study, in vitro anticariogenic potential of ethyl acetate, hexane and methanol and aqueous extracts of plant leaves of Eucalyptus globules Labill. were evaluated by using four cariogenic bacteria, Lactobacillus acidophilus, Lactobacillus casei, Staphylococcus aureus and Streptococcus mutans. Agar well diffusion method and minimum inhibitory concentration (MIC) were used for this purpose. The ethyl acetate extracted fraction of plant leaves showed good inhibitory effects against all selected bacteria. In Eucalyptus globules, hexane and ethyl acetate extracts found highly effective against, Lactobacillus acidophilus with MIC value of 0.031 and 0.062 mg/mL, respectively. Qualitative phytochemical investigation of above extracts showed the presence of alkaloids, phenolic compounds, steroids, cardiac glycosides and terpenes. Based on the MIC value and bioautography, ethyl acetate of plant leaf was selected for further study. Further investigation on the structure elucidation of the bioactive compound using IR, GC-MS and NMR techniques revealed the presence of alpha-farnesene, a sesquiterpene. Eucalyptus globules plant leaf extracts have great potential as anticariogenic agents that may be useful in the treatment of oral disease.

Difference in initial dental biofilm accumulation between night and day

OBJECTIVE

The study of initial microbial colonization on dental surfaces is a field of intensive research because of the aetiological role of biofilms in oral diseases. Most previous studies of de novo accumulation and composition of dental biofilms in vivo do not differentiate between biofilms formed during day and night. This study hypothesized that there is a diurnal variation in the rate of accumulation of bacteria on solid surfaces in the oral cavity.

MATERIALS AND METHODS

In situ biofilm from healthy individuals was collected for 12 h during day and night, respectively, subjected to fluorescent in situ hybridization and visualized using confocal laser scanning microscopy.

RESULTS

Analysis of the biofilms using stereological methods and digital image analysis revealed a consistent statistically significant difference between both the total number of bacteria and the biovolume in the two 12-h groups (p = 0.012), with the highest accumulation of bacteria during daytime (a factor of 8.8 and 6.1 higher, respectively). Hybridization with probes specific for streptococci and Actinomyces naeslundii indicated a higher proportion of streptococci in biofilms grown during daytime as compared to night-time. No differences could be observed for A. naeslundii. The degree of microbial coverage and the bacterial composition varied considerably between different individuals.

CONCLUSION

The data provide firm evidence that initial biofilm formation decreases during the night, which may reflect differences in the availability of salivary nutrients. This finding is of significant importance when studying population dynamics during experimental dental biofilm formation.

XTT assay of ex vivo saliva biofilms to test antimicrobial influences

OBJECTIVE

Many dental diseases are attributable to biofilms. The screening of antimicrobial substances, in particular, requires a high sample throughput and a realistic model, the evaluation must be as quick and as simple as possible. For this purpose, a colorimetric assay of the tetrazolium salt XTT (sodium 3'-[1-[(phenylamino)-carbony]-3,4-tetrazolium]-bis(4-methoxy-6-nitro)benzene-sulfonic acid hydrate) converted by saliva biofilms is recommended. Cleavage of XTT by dehydrogenase enzymes of metabolically active cells in biofilms yields a highly colored formazan product which is measured photometrically.

MATERIALS AND METHOD

The suitability of the XTT assay for detecting the vitality of ex vivo saliva biofilms was tested to determine the efficacy of chlorhexidine and ozone versus saliva biofilms grown on titanium discs.

RESULTS

The XTT method lends itself to testing the vitality of microorganisms in saliva biofilms. The sensitivity of the arrays requires a specific minimum number of pathogens, this number being different for planktonic bacteria and those occurring in biofilms. The antibacterial effect after treatment with chlorhexidine or ozone was measured by XTT conversion that was significantly reduced. The antimicrobial efficacy of 60 s 0.5% and 0.1% chlorhexidine treatment was equal and comparable with 60 s ozone treatment.

CONCLUSION

The XTT assay is a suitable method to determine the vitality in saliva biofilms, permitting assessment of the efficacy of antimicrobial substances. Its quick and easy applicability renders it especially suitable for screening.

Nisin inhibits dental caries-associated microorganism in vitro

Nisin, produced by Lactococcus lactis, is an antibiotic peptide to effectively antagonize a broad spectrum of Gram-positive bacteria, and is widely used as a safe food antimicrobial agent. In the present study, we investigated whether nisin could be used as an effective antibiotic peptide against the nine common cariogenic microorganisms, and its antimicrobial activity could be affected by the ingredients of saliva in oral cavity. In the minimal inhibitory concentration (MIC) and minimal bactericide concentration (MBC) and spot-on-lawn assay, nisin displayed different MIC, MBC and antimicrobial activity against the nine tested strains. There was statistical difference between the inhibitory zone diameters of nisin against the different tested bacteria (p<0.05), but no statistical difference between the inhibitory zone diameters of nisin dissolved in PBS and saliva (p>0.05). Furthermore, morphology and membranes of Streptococcus sanguinis, Streptococcus mutans, Lactobacillus fermenti and Lactobacillus acidophilus with nisin treatment were observed and showed different degrees of variation by a Field Emission Scanning Electron Microscope (FE-SEM). Our findings suggested that nisin has considerable potential for prevention and treatment of dental caries.

Quantitative analysis of adhesion of cariogenic streptococci to orthodontic raw materials

INTRODUCTION

Knowledge of adhesion patterns of cariogenic streptococci to orthodontic materials can provide valuable information on the cause of enamel demineralization during orthodontic treatment. The purpose of this study was to investigate the adhesion of 2 cariogenic streptococci strains to 7 orthodontic raw materials (3 light-cured orthodontic adhesives, 3 bracket raw materials, and hydroxyapatite) with respect to bacterial species, incubation time, and saliva coating.

METHODS

Each material was incubated with unstimulated whole saliva or phosphate-buffered saline solution for 2 hours. Binding assays were then performed by incubating tritium-labeled cariogenic streptococci with each raw material for 3 or 6 hours.

RESULTS

The degree of adhesion varied by material type. Generally, adhesion of cariogenic streptococci was significantly higher for bonding adhesives than for bracket materials, and adhesion to resin-modified glass ionomer was the highest. A longer incubation time generally increased bacterial adhesion, whereas saliva coating did not significantly influence bacterial adhesion.

CONCLUSIONS

Bonding adhesives around brackets should be removed carefully during the bonding procedure to avoid enamel decalcification.

In vitro inhibition of oral streptococci binding to the acquired pellicle by algal lectins

AIMS

The initial colonization of the tooth by streptococci involves their attachment to adsorbed components of the acquired pellicle. Avoiding this adhesion may be successful in preventing caries at early stages. Salivary mucins are glycoproteins that when absorbed onto hydroxyapatite may provide binding sites for certain bacteria. Algal lectins may be especially interesting for oral antiadhesion trials because of their great stability and high specificity for mucins. This work aimed to evaluate the potential of two algal lectins to inhibit the adherence of five streptococci species to the acquired pellicle in vitro.

METHODS AND RESULTS

The lectins used were extracted from Bryothamnion triquetrum (BTL) and Bryothamnion seaforthii (BSL). Fluorescence microscopy was applied to visualize the ability of fluorescein isothiocyanate-labelled lectins to attach to the pellicle and revealed a similar capability for both lectins. Streptococcal adherence assays were performed using saliva-coated microtitre plates. BSL inhibited more than 75% of Streptococcus sanguis, Streptococcus mitis, Streptococcus sobrinus and Streptococcus mutans adherence, achieving 92% to the latter. BTL only obtained statistically significant results on S. mitis and S. sobrinus, whose adherence was decreased by 32.5% and 54.4%, respectively.

CONCLUSION

Algal lectins are able to inhibit streptococcal adherence.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results support the proposed application of lectins in antiadhesion therapeutics.

Socioeconomic and sociodemographic variables associated with oral hygiene status in Mexican schoolchildren aged 6 to 12 years

BACKGROUND

The purpose of this study was to identify the socioeconomic and sociodemographic variables associated with oral hygiene status in schoolchildren aged 6 to 12 years in Navolato, Sinaloa, Mexico.

METHODS

A cross-sectional study was carried out in 3,048 schoolchildren. A questionnaire was used to determine socioeconomic and sociodemographic variables, and a clinical oral examination was carried out to establish oral hygiene status. The "plaque" component of the simplified oral hygiene index (S-OHI) was the criterion used to determine oral hygiene status in children. Using principal component analysis, five socioeconomic factors were streamlined to one principal component to determine the individual socioeconomic level. Data were analyzed with non-parametric tests and multivariable logistic regression.

RESULTS

The population included 1,456 boys and 1,592 girls. The mean value for S-OHI was 1.10 +/- 0.34. The largest percentage (50.8%) of the S-OHI scores ranged between 0 and 1. In the multivariate model, younger age, male gender, and lower toothbrushing frequency (P <0.05) were associated with poor oral hygiene. Children with better socioeconomic status had better oral hygiene (P <0.05).

CONCLUSIONS

Most children ( approximately 60%) had an acceptable level of oral hygiene. Diverse variables were associated with oral hygiene in these Mexican children, highlighting a gradient distribution throughout the socioeconomic spectrum. It is necessary to implement strategies that would help to diminish the disparities observed across diverse socioeconomic groups.

The effect of Piper betle and Psidium guajava extracts on the cell-surface hydrophobicity of selected early settlers of dental plaque

The adhesion of early settlers of dental plaque to the tooth surface has a role in the initiation of the development of dental plaque. The hydrophobic surface properties of the bacteria cell wall are indirectly responsible for the adhesion of the bacteria cell to the acquired pellicle on the tooth surfaces. In this study, the effect of aqueous extract of two plants (Psidium guajava and Piper betle) on the cell-surface hydro-phobicity of early settlers of dental plaque was determined in vitro. Hexadecane, a hydrocarbon was used to represent the hydrophobic surface of the teeth in the oral cavity. It was found that treatment of the early plaque settlers with 1 mg/ml extract of Psidium guajava reduced the cell-surface hydrophobicity of Strep. sanguinis, Strep. mitis and Actinomyces sp. by 54.1%, 49.9% and 40.6%, respectively. Treatment of these bacteria with the same concentration of Piper betle however, showed a comparatively lesser effect (< 10%). It was also observed that the anti-adhesive effect of the two extracts on the binding of the early plaque settlers to hexadecane is concentration dependent.

Effect of material characteristics and/or surface topography on biofilm development

BACKGROUND

From an ecological viewpoint, the oral cavity, in fact the oro-pharynx, is an 'open growth system'. It undergoes an uninterrupted introduction and removal of both microorganisms and nutrients. In order to survive within the oro-pharyngeal area, bacteria need to adhere either to the soft or hard tissues in order to resist shear forces. The fast turn-over of the oral lining epithelia (shedding 3 x/day) is an efficient defence mechanism as it prevents the accumulation of large masses of microorganisms. Teeth, dentures, or endosseous implants, however, providing non-shedding surfaces, allow the formation of thick biofilms. In general, the established biofilm maintains an equilibrium with the host. An uncontrolled accumulation and/or metabolism of bacteria on the hard surfaces forms, however, the primary cause of dental caries, gingivitis, periodontitis, peri-implantitis, and stomatitis.

OBJECTIVES

This systematic review aimed to evaluate critically the impact of surface characteristics (free energy, roughness, chemistry) on the de novo biofilm formation, especially in the supragingival and to a lesser extent in the subgingival areas.

METHODS

An electronic Medline search (from 1966 until July 2005) was conducted applying the following search items: 'biofilm formation and dental/oral implants/surface characteristics', 'surface characteristics and implants', 'biofilm formation and oral', 'plaque/biofilm and roughness', 'plaque/biofilm and surface free energy', and 'plaque formation and implants'. Only clinical studies within the oro-pharyngeal area were included.

RESULTS

From a series of split-mouth studies, it could be concluded that both an increase in surface roughness above the R(a) threshold of 0.2 microm and/or of the surface-free energy facilitates biofilm formation on restorative materials. When both surface characteristics interact with each other, surface roughness was found to be predominant. The biofilm formation is also influenced by the type (chemical composition) of biomaterial or the type of coating. Direct comparisons in biofilm formation on different transmucosal implant surfaces are scars.

CONCLUSIONS

Extrapolation of data from studies on different restorative materials seems to indicate that transmucosal implant surfaces with a higher surface roughness/surface free energy facilitate biofilm formation.

Cranberry high molecular weight constituents promote Streptococcus sobrinus desorption from artificial biofilm

Dental biofilm harbouring oral bacteria is highly correlated with the progression of dental diseases. Disruption of biofilm formation via anti-adhesion agents is an alternative means to the antibacterial approach. Previous studies have shown that high molecular weight non-dialysable material (NDM) derived from cranberry juice inhibits the adhesion of Escherichia coli and the coaggregation of a variety of oral bacteria. In addition, it inhibits the formation of glucans and fructans synthesised by GTF and FTF. In the present study, we examined the anti-adhesion effect of NDM on S. sobrinus. NDM promoted desorption of S. sobrinus from biofilm in the presence and absence of extracellular glucans and fructans, although the effect was more pronounced in the absence of these polysaccharides. Precoating of the bacteria with NDM reduced their ability to form biofilm. Our results indicate that NDM could be exploited as an anti-biofilm agent.

Adhesion of oral streptococci to experimental bracket pellicles from glandular saliva

The aim of this study was to evaluate the functions of bracket pellicles as the binding receptors for Streptococcus mutans and Streptococcus gordonii. Four different types of orthodontic brackets were used: stainless steel, monocrystalline sapphire, polycrystalline alumina, and plastic. The bracket pellicles were formed by incubating orthodontic brackets with fresh submandibular-sublingual saliva or parotid saliva for 2 hours. The pellicles were extracted, and their components were confirmed by gel electrophoresis, immunodetection, and amino acid composition analysis. The roles of the bracket pellicles in the adhesion of oral streptococci were evaluated by incubating tritium-labeled streptococci with pellicle-transfer blots. The results showed that the salivary components adhered selectively according to type of bracket and glandular saliva. The selective adsorption was also proven by the amino acid composition profiles. Among the several salivary proteins, MG2, alpha-amylase, and the acidic proline-rich proteins provided the binding sites for S gordonii. However, none of these proteins in the bracket pellicles contributed to the adhesion of S mutans. These findings suggest that numerous salivary proteins can adhere selectively to the orthodontic brackets, and some of them contribute to the binding of S gordonii.

Supragingival calculus: formation and control

Dental calculus is composed of inorganic components and organic matrix. Brushite, dicalcium phosphate dihydrate, octacalcium phosphate, hydroxyapatite, and whitlockite form the mineral part of dental calculus. Salivary proteins selectively adsorb on the tooth surface to form an acquired pellicle. It is followed by the adherence of various oral micro-organisms. Fimbriae, flagella, and some other surface proteins are essential for microbial adherence. Microbial co-aggregation and co-adhesion enable some micro-organisms, which are incapable of adhering, to adhere to the pellicle-coated tooth surface. Once organisms attach to the tooth surface, new genes could be expressed so that mature dental plaque can form and biofilm bacteria assume increased resistance to antimicrobial agents. Supersaturation of saliva and plaque fluid with respect to calcium phosphates is the driving force for plaque mineralization. Both salivary flow rate and plaque pH appear to influence the saturation degree of calcium phosphates. Acidic phospholipids and specific proteolipids present in cell membranes play a key role in microbial mineralization. The roles of crystal growth inhibitors, promoters, and organic acids in calculus formation are discussed. Application of biofilm culture systems in plaque mineralization is concisely reviewed. Anti-calculus agents used--centering on triclosan plus polyvinyl methyl ether/maleic acid copolymer, pyrophosphate plus polyvinyl methyl ether/maleic acid copolymer, and zinc ion-in commercial dentifrices are also discussed in this paper.

Roles of salivary proteins in the adherence of oral streptococci to various orthodontic brackets

Knowledge of salivary pellicles on orthodontic brackets provides a better understanding of microbial adherence. The aim of this study was to analyze the effects of bracket pellicles on the adherence of Streptococcus gordonii and Streptococcus mutans. Bracket pellicles were formed by the incubation of 4 kinds of orthodontic brackets with unstimulated whole saliva for 2 hrs, and analyzed by electrophoresis, immunodetection, and amino acid analysis. Binding assays were then performed by the incubation of tritium-labeled streptococci with the pellicle-transfer blots and orthodontic brackets. The results showed that low-molecular-weight mucin, alpha-amylase, secretory IgA, acidic proline-rich proteins, and cystatins adhered to all kinds of brackets, though the amino acid composition of pellicles differed between bracket types. Some of these proteins increased the binding of S. gordonii to saliva-coated brackets. However, salivary pellicles decreased the binding of S. mutans. Collectively, salivary pellicles were found to play a significant role in the initial adhesion of oral streptococci to orthodontic brackets.

Comparison of corrosion behaviour in presence of oral bacteria

The aim of this study was to compare the resistance of the corrosion of dental alloys in a solution containing oral bacteria named Actinomyces viscosus (ATCC19246). In this paper, we explain the choice of this precise species of bacteria, then specify its culture in artificial saliva and the experimental precautions needed to avoid the pollution by other bacteria. The electrochemical behaviour of two dental alloys (Ni-Cr alloy and gold-based alloy) was investigated by electrochemical means in sterile Fusayama artificial saliva (AS), AS enriched with sterile yeast extract (YE) and YE modified by introducing bacteria (AV). Open-circuit potentials, potentiodynamic curves, polarization resistance and impedance spectroscopy are the electrochemical procedures selected for this work. It has thus been shown that the open-circuit potential of the non-precious alloy is always lower than that of the gold precious alloy, and the colonization of metal surface by bacteria caused a drop in open circuit potential. The electrochemical impedance spectroscopy results have shown that the electrolyte resistance decreased between the AS, YE and AV milieu, in the presence of bacteria a slight decrease in polarization resistance was observed with the precious alloy and an increase with the non-precious alloy. The drop in the electrolyte resistance cannot explain the change in polarization resistance. The influence of Actinomyces viscosus might be essentially due to the consumption of oxygen at the metal/electrolyte interface of the specimen. For the non-precious alloy, the absence of oxygen (instigator of corrosion) led to an increase in polarization resistance whereas the slight decrease for the precious alloys might be justified by the organic and inorganic metabolites released by bacteria in to the electrolyte. The scanning electron micrography after electrochemical analysis, confirmed the absence of contaminants. These preliminary results demonstrate the unquestionable influence of this bacteria on the corrosion behaviour of the alloys studied, however, further studies are necessary.

A continuous culture biofilm model of cariogenic responses

AIMS

To validate an in vitro model for the analysis of physiological and ecological responses to sugar challenge in bacterial populations, and subsequent changes in enamel mineralization.

METHODS AND RESULTS

A seven-organism bacterial consortium was grown in a biofilm mode on enamel and hydroxyapatite (HA) surfaces in a continuous culture system and exposed to repeated sucrose challenges. This produced 'pH-cycling' conditions within the system. Populations on HA surfaces were enumerated. Changes in relative proportions of the different populations, and in the total viable count, were observed, between different treatments. Microradiography of the enamel sections showed increasing demineralization with increasing sucrose concentration. The lesions formed were similar to 'white-spot' lesions found in vivo. Differences in the quality of biofilms formed were also observed using Confocal Laser Scanning Microscopy.

CONCLUSION

An in vitro model has been validated for the analysis of both physiological and ecological responses to sucrose challenges in bacterial populations, and subsequent changes in enamel mineralization.

SIGNIFICANCE AND IMPACT OF THE STUDY

This model should facilitate the study of changes in bacterial populations in response to application of putative anticaries agents and concomitant changes in enamel mineralization.

Periodontal tissue responses after insertion of artificial crowns and fixed partial dentures

PURPOSE

The purpose of this review was, first, to critically evaluate published evidence on the effects of artificial crowns and fixed partial dentures (FPDs) on adjacent periodontal tissue health, and second to synthesize this evidence into meaningful summaries. Restoration qualities that contribute to inflammatory responses were identified based on strength of evidence, and variables that should be controlled in future investigations were outlined. Such information is necessary to accurately predict the prognosis of periodontal tissues adjacent to crowns or FPDs.

METHODS

Clinical trial and epidemiologic evidence published in English was collected. The effects of crowns or FPDs on gingival inflammation, probing depths, and bone loss were evaluated based on accuracy of measurement, reliability of measurement, and/or appropriateness of data analysis.

RESULTS

Crowns and FPDs increased the incidence of advanced gingival inflammation adjacent to restorations, particularly if restorations had intracrevicular finish line placement, poor marginal adaptation, or rough surfaces. However, because of the limitation in the accuracy and reliability of probing depth measurements, reports of greater mean probing depths of crowned teeth, which tended to be less than 1 mm greater than control teeth, should be questioned. Finally, crowns and FPDs in general did not accelerate the rate of adjacent bone loss.

CONCLUSION

Clinically deficient restorations, as well as clinically acceptable restorations, can contribute to gingival inflammation. However, with the limitations of the applied methods of measurement, current evidence has not shown an increased attachment loss adjacent to crowns or FPDs. Future trials should document periodontal health before therapy and periodically after restoration insertion so that each tooth serves as its own control. In future studies, the periodontal disease history of the patient, the influence of the restoration on plaque formation, and the composition of the crevicular microflora must be recorded.

Prevention of periodontal disease

Periodontal disease is the most common disease affecting adult dogs and cats. It is also a very preventable disease. The insidious nature of the disease and requirement for the pet owner to be actively involved make client and public education absolutely vital. Although clients are commonly aware of their pets' bad breath, they rarely notice gingivitis, fractured teeth, and traumatic malocclusions. The annual National Pet Dental Health Month program has resulted in a tremendous increase in public awareness. Veterinarians must carry this further in their everyday practices, convincing our clients of the need for preventive dental care. It is only through clients' ongoing desire and persistence that a long-term preventive program can be successful. This requires a coordinated effort by the entire hospital staff. When successful, clients' pets will live healthier and longer lives.

The specificity and affinity of immunoliposome targeting to oral bacteria

Immunoliposomes have been prepared using antibodies raised to an antigenic determinant on the cell surface of the oral bacterium Streptococcus oralis (S. oralis) in an investigation of their potential to reduce dental plaque. The N-succinimidyl-S-acetylthioacetate (SATA) derivative of the antibodies were conjugated through the reactive m-maleimidobenzoyl-N-hydroxysuccinimide (MBS) derivative of dipalmitoyl-phosphatidylethanolamine (DPPE) incorporated into liposomes. The degree of antibody conjugation to the liposomes was controlled by the percentage of DPPEMBS incorporated into the liposomes. The chemical modification of the antibodies did not affect the ability of the antibodies to bind to a S. oralis biofilm. However, the affinity of the immunoliposomes for S. oralis was much lower than that of the free antibody. The anti-oralis antibodies were highly specific for S. oralis. The anti-oralis immunoliposomes showed the greatest affinity for S. oralis, when targeted to a range of different oral bacterial biofilms. The immunoliposome targeting affinity for S. oralis was largely unaffected by the number of antibodies conjugated to the liposomal surface or by the net charge of the liposomal lipid bilayer. The immunoliposomes showed a greater affinity for S. oralis than 'naked' (bearing no antibody) liposomes. However, positively charged liposomes, incorporating stearylamine, adsorbed to S. oralis with greater affinities than the immunoliposomes. The immunoliposomes appeared to be physically stable over a period of 18 months, as judged by particle-size measurements.

Detachment of linking film bacteria from enamel surfaces by oral rinses and penetration of sodium lauryl sulphate through an artificial oral biofilm

The biofilm mode of growth protects plaque micro-organisms against environmental attacks, such as from antimicrobials or detergents. Dental plaque is linked to enamel through the adhesion of initial colonizers. Once this link is disrupted, the entire plaque mass adhering to it detaches. Experiments in a parallel-plate flow chamber demonstrated that bacteria adhering to saliva-coated enamel could not be stimulated to detach by perfusion of the flow chamber with two traditional mouthrinses (Corsodyl and Scope), whereas perfusion with a prebrushing rinse (Plax) or its detergent components stimulated detachment from saliva-coated enamel of a wide variety of bacterial strains. Following perfusion of the flow chamber with the mouthrinses, little additional detachment of adhering bacteria by the passage of a liquid-air interface occurred. After perfusion with the prebrushing rinse, however, significant numbers of still-adhering bacteria could be stimulated to detach by passage of a liquid-air interface, indicating that Plax had weakened their adhesive bond. The ability of Plax or its detergent components to detach plaque bacteria is not always obvious from in vivo experiments, and reports on its clinical efficacy are inconsistent. Likely, antimicrobials or detergents are unable to penetrate the plaque and reach the linking film bacteria, as demonstrated here by Fourier transform infrared spectroscopy.

Dental calculus: recent insights into occurrence, formation, prevention, removal and oral health effects of supragingival and subgingival deposits

Dental calculus, both supra- and subgingival occurs in the majority of adults worldwide. Dental calculus is calcified dental plaque, composed primarily of calcium phosphate mineral salts deposited between and within remnants of formerly viable microorganisms. A viable dental plaque covers mineralized calculus deposits. Levels of calculus and location of formation are population specific and are affected by oral hygiene habits, access to professional care, diet, age, ethnic origin, time since last dental cleaning, systemic disease and the use of prescription medications. In populations that practice regular oral hygiene and with access to regular professional care, supragingival dental calculus formation is restricted to tooth surfaces adjacent to the salivary ducts. Levels of supragingival calculus in these populations is minor and the calculus has little if any impact on oral-health. Subgingival calculus formation in these populations occurs coincident with periodontal disease (although the calculus itself appears to have little impact on attachment loss), the latter being correlated with dental plaque. In populations that do not practice regular hygiene and that do not have access to professional care, supragingival calculus occurs throughout the dentition and the extent of calculus formation can be extreme. In these populations, supragingival calculus is associated with the promotion of gingival recession. Subgingival calculus, in "low hygiene" populations, is extensive and is directly correlated with enhanced periodontal attachment loss. Despite extensive research, a complete understanding of the etiologic significance of subgingival calculus to periodontal disease remains elusive, due to inability to clearly differentiate effects of calculus versus "plaque on calculus". As a result, we are not entirely sure whether subgingival calculus is the cause or result of periodontal inflammation. Research suggests that subgingival calculus, at a minimum, may expand the radius of plaque induced periodontal injury. Removal of subgingival plaque and calculus remains the cornerstone of periodontal therapy. Calculus formation is the result of petrification of dental plaque biofilm, with mineral ions provided by bathing saliva or crevicular fluids. Supragingival calculus formation can be controlled by chemical mineralization inhibitors, applied in toothpastes or mouthrinses. These agents act to delay plaque calcification, keeping deposits in an amorphous non-hardened state to facilitate removal with regular hygiene. Clinical efficacy for these agents is typically assessed as the reduction in tartar area coverage on the teeth between dental cleaning. Research shows that topically applied mineralization inhibitors can also influence adhesion and hardness of calculus deposits on the tooth surface, facilitating removal. Future research in calculus may include the development of improved supragingival tartar control formulations, the development of treatments for the prevention of subgingival calculus formation, the development of improved methods for root detoxification and debridement and the development and application of sensitive diagnostic methods to assess subgingival debridement efficacy.