Bacteriological Evaluation of Gingival Crevicular Fluid in Teeth Restored Using Fixed Dental Prostheses: An In Vivo Study

The present in vivo study determined the microbiological counts of the gingival crevicular fluid (GCF) among patients with fixed dental prostheses fabricated using three different techniques. A total of 129 subjects were divided into three study groups: first, cobalt-chrome-based, metal-ceramic prostheses fabricated by the conventional method (MC, n = 35); the second group consisted of cobalt-chrome-based, metal-ceramic prostheses fabricated by the computer-aided design and computer-aided manufacturing (CAD/CAM) technique (CC-MC, n = 35); the third group comprised zirconia-based ceramic prostheses fabricated using the CAD/CAM technique (CC-Zr, n = 35). The control consisted of 24 patients using prostheses fabricated with either MC, CC-MC, or CC-Zr. The GCF was obtained from the subjects before treatment, and 6 and 12 months after the prosthetic treatment. Bacteriological and bacterioscopic analysis of the GCF was performed to analyze the patients’ GCF. The data were analyzed using SPSS V20 (IBM Company, Chicago, IL, USA). The number of microorganisms of the gingival crevicular fluid in all groups at 12 months of prosthetic treatment reduced dramatically compared with the data obtained before prosthetic treatment. Inflammatory processes in the periodontium occurred slowly in the case of zirconium oxide-based ceramic constructions due to their biocompatibility with the mucous membranes and tissues of the oral cavity as well as a reduced risk of dental biofilm formation. This should be considered by dentists and prosthodontists when choosing restoration materials for subjects with periodontal pathology.

A 3D printed microfluidic flow-cell for microscopy analysis of in situ-grown biofilms

Biofilm phenomena ranging from metabolic processes to attachment, detachment and quorum sensing are influenced by the fluid flow across the biofilm. A number of commercially available flow-cells allow for microscopy analysis of laboratory biofilms under flow, but there is a lack of shear controlled microfluidic devices that accommodate biofilms grown in situ on carriers or tissue samples. Therefore, we developed a flow-cell with adjustable geometry for microscopy analysis of in situ-grown biofilm samples under shear-controlled flow. The flow-cells were designed as one-piece disposable models, 3D-printed in resin and sealed with a coverslip after insertion of the biofilm sample. As a proof of concept, we studied the impact of stimulated saliva flow on pH developments in in situ-grown dental biofilms exposed to sucrose. Under static conditions, pH dropped in the biofilms, with pronounced differences between individual biofilms, but also between different microscopic fields of view within one biofilm. pH in the top layer of the biofilms tended to be lower than pH in the bottom layer. Under conditions of stimulated saliva flow (5 mm/min), pH rose to neutral or slightly alkaline values in all biofilms, and the vertical gradients were reversed, with the biofilm bottom becoming more acidic than the top. Hence, the present work demonstrates the importance of flow for the study of pH in dental biofilms.

The underestimated problem of oral Candida colonization-An observational pilot study in one nursing home

Objectives

Older people are at increased risk of intraoral yeast colonization. In this observational case series, we assessed Candida colonization among nine nursing home residents to investigate possible correlations with their individual characteristics, general health parameters, and oral care. We also described the effect of professional dental cleaning (PDC) including prosthesis cleaning on colonization cases.

Materials and methods

General clinical and oral health was assessed in nine residents, and samples were taken from six oral mucosa sites or prosthetic surfaces. PDC was performed to achieve macroscopically clean results, and residents were re-examined 2 weeks later.

Results

We found that six residents were intraorally colonized with Candida albicans; four also had Candida glabrata. Prostheses were particularly infected. Dementia, multimorbidity, and presence of prostheses reduced oral hygiene ability; requiring assistance for oral hygiene care was a risk indicator for Candida colonization. PDC reduced C. albicans (at the expense of increased C. glabrata) but was not optimal for maintaining Candida reduction.

Conclusion

In this pilot study, Candida colonization is prevalent among nursing home residents, especially those with cognitive impairment, multimorbidity, or reduced oral hygiene capacity. Potential negative effects on general health necessitate diagnostic and therapeutic guidelines. PDC alone did not maintain the reduction in Candida colonization; additional methods for daily oral care are necessary.

Silver Nanoparticles Addition in Poly(Methyl Methacrylate) Dental Matrix: Topographic and Antimycotic Studies

The widespread use of nanoparticles (NPs) in medical devices has opened a new scenario in the treatment and prevention of many diseases and infections owing to unique physico-chemical properties of NPs. In this way, silver nanoparticles (AgNPs) are known to have a strong antimicrobial activity, even at low concentrations, due to their ability to selectively destroy cellular membranes. In particular, in the field of dental medicine, the use of AgNPs in different kinds of dental prosthesis matrixes could be a fundamental tool in immunodepressed patients that suffer of different oral infections. Candida albicans (C. albicans), an opportunistic pathogenic yeast with high colonization ability, is one of the causative agents of oral cavity infection. In our work, we added monodispersed citrate-capping AgNPs with a size of 20 nm at two concentrations (3 wt% and 3.5 wt%) in poly(methyl methacrylate) (PMMA), the common resin used to develop dental prostheses. After AgNPs characterization, we evaluated the topographical modification of PMMA and PMMA with the addition of AgNPs by means of atomic force microscopy (AFM), showing the reduction of surface roughness. The C. albicans colonization on PMMA surfaces was assessed by the Miles and Misra technique as well as by scanning electron microscopy (SEM) at 24 h and 48 h with encouraging results on the reduction of yeast viability after AgNPs exposure.

Effect of Type II Diabetes Mellitus, Candida Albicans and Streptococcus Mutans on the Biofilm Formation on Prosthetic Materials

AIM

To investigate the biofilm formation on Prosthetic materials as affected by type II diabetes mellitus, Candida albicans and Streptococcus mutans.

MATERIALS AND METHODS

Two types of saliva, natural saliva, and artificial saliva were collected and prepared respectively. The natural saliva was divided into diabetic and non-diabetic saliva. The artificial saliva was further divided into two groups, one inoculated with Streptococcus mutans and the second with Candida albicans. The 150 samples of various prosthetic materials were prepared using nickel-chromium alloy, ceramic, soft liner, tooth molding powder; heat cured the acrylic resin. The samples were then immersed in natural saliva and artificial saliva and studied for biofilm formation.

RESULTS

Diabetic saliva formed more biofilm than non-diabetic saliva. Streptococcus mutans were able to form more biofilm than Candida albicans in artificial saliva on constitutive androstane receptor (hCAR) and spinal length (SL). In Diabetic saliva, there was a significant difference in the biofilm formation seen between MC and NCA (p < 0.05). No biofilm was formed on hCAR in natural saliva (diabetic or non-diabetic). In artificial saliva inoculated with Candida albicans and streptococcus mutans there is a significant difference in the biofilm formation in all the materials except NCA.

CONCLUSION

Diabetic saliva has more potential to form biofilm than non-diabetic saliva. Also, Candida albicans and Streptococcus mutans both can form a biofilm on materials used with the maximum formation on hCAR. Smoother materials formed less biofilm than rougher surfaces like hCAR, PCM, SL.

CLINICAL SIGNIFICANCE

It is desirable for dental restorative materials to have a low susceptibility for accumulation and formation of biofilm as it may lead to pathologies such as dental caries, periodontal disease, peri-implantitis, etc. which are plaque-related. The most commonly used materials in prosthodontics have been used in the study to establish a direct relationship with the formation of biofilm, this, in turn, helps us to take the right call in choosing a material for a patient with an already compromised systemic condition.

Influence of Dental Prosthesis and Restorative Materials Interface on Oral Biofilms

Oral biofilms attach onto both teeth surfaces and dental material surfaces in oral cavities. In the meantime, oral biofilms are not only the pathogenesis of dental caries and periodontitis, but also secondary caries and peri-implantitis, which would lead to the failure of clinical treatments. The material surfaces exposed to oral conditions can influence pellicle coating, initial bacterial adhesion, and biofilm formation, due to their specific physical and chemical characteristics. To define the effect of physical and chemical characteristics of dental prosthesis and restorative material on oral biofilms, we discuss resin-based composites, glass ionomer cements, amalgams, dental alloys, ceramic, and dental implant material surface properties. In conclusion, each particular chemical composition (organic matrix, inorganic filler, fluoride, and various metallic ions) can enhance or inhibit biofilm formation. Irregular topography and rough surfaces provide favorable interface for bacterial colonization, protecting bacteria against shear forces during their initial reversible binding and biofilm formation. Moreover, the surface free energy, hydrophobicity, and surface-coating techniques, also have a significant influence on oral biofilms. However, controversies still exist in the current research for the different methods and models applied. In addition, more in situ studies are needed to clarify the role and mechanism of each surface parameter on oral biofilm development.

Characterization of Oral Microbiota in Removable Dental Prosthesis Users: Influence of Arterial Hypertension

INTRODUCTION

Studies have described the possible relation between oral infections and atherosclerotic events.

OBJECTIVE

To characterize the oral microbiota of normotensive and hypertensive users of dental prostheses.

METHODS

The sample consisted of 41 complete dental prosthesis users, divided into groups: 21 participants with systemic arterial hypertension and 20 normotensive participants. The data collection included the characteristics of the sociodemographic variables and the determination of the microbial load in the saliva. For the descriptive analyses, Statistical Package for the Social Sciences was used. The description of the proportional differences between the groups was based on the application of Mann-Whitney's statistical test. Statistical significance was set at 5% (p < 0.05).

RESULTS

The analysis of the oral microbiota showed the vast growth of aerobic microorganisms in all samples from both groups. The microbial load of streptococci and staphylococci was significantly higher among hypertensive participants. Candida yeasts were detected in the saliva culture of most samples. The hypertensive participants rank in the category of very high colonization index/high risk of infection related to this microorganism.

CONCLUSIONS

The mouth of dental prosthesis users, especially when hypertensive, can constitute an important reservoir of pathogens, indicating an established inflammatory or infectious condition or risk for developing this condition.

[STUDY OF COLONIZATION PROCESSES AND PERSISTENCE OF MICROORGANISMS IN ARTIFICIAL MATERIALS FOR MEDICAL USE]

AIM

Study processes of microbial colonization and persistence of microorganisms in polymer materials for medical use.

MATERIALS AND METHODS

Samples (1 x 1 cm plates) of polymer plastics for production of removable dental prosthesis based on polyurethane and acryl were used, that were incubated with clinical isolates of Pseudomonas aeuruginosa, Staphylococcus aureus in Luria-Bertani broth nutrient media for 24, 48 hours and 7, 14 days and for 1, 5 and 3 months at a temperature of 37 degrees C. Dynamics of interaction process of microorganisms with polymer materials were studied using scanning electron microscope Quanta 200 3D (FEI Company, USA). The samples were fixated after incubation with 10% of neutral formaldehyde, dehydration with alcohols or acetone, typical for SEM, was not carried out, that allowed to conserve the native structure of the samples, including exo-cell matrix of biofilms.

RESULTS

Electron-microscopical data on stages of interaction of bacteria with the surface of medical plastics were obtained. Biofilms were shown to be formed on abiotic surfaces and biodestructive changes of plastics appeared. A question on the possibility of prolonged persistence of pathogenic for human microorganisms in artificial prosthesis is discussed.

CONCLUSION

The developed experimental model of formation of biofilm on abiotic surfaces could be the basis for carrying out studies directed on the fight with biofilms, by using SEM.

[Antiadhesive properties of the surfactants of Acinetobacter calcoaceticus IMB B-7241, Rhodococcus erythropolis IMB Ac-5017, and Nocardia vaccinii IMB B-7405]

Attachment of the cells of some bacteria, yeasts, and micromycetes to various surfaces (catheters, dentures, plastic, polyvinyl chloride, tiles, and steel) treated with the surfactants fromAcinetobacter calcoace- ticus IMB B-7241, Rhodococcus erythropolis IMB Ac-5017, and Nocardia vaccinii IMB B-7405 was studied. Adhesion of microorganisms to all the studied surfaces depended on the surfactant concentration and purity, kind of surface, and the test culture. Treatment with the surfactants from N. vaccinii IMB B-7405 (0.005- 0.05 mg/mL), A. calcoaceticus IMB B-7241 (0.003-0.036 mg/mL), and R. erythropolis IMB Ac-5017 (0.03- 0.12 mg/mL) resulted in adhesion decreased respectively by 35-75, 60-75, and 25-90% for bacteria (Es- cherichia coli IEM-1, Bacillus subtilis BT-2, etc.), by 80-85, 55-90, and 15-60% for yeasts Candida albicans D-6, and by 40-50, 35-45, and 10-20% for micromycetes (Aspergillus niger P-3 and Fusarium culmorum T-7).

Candida albicans and denture stomatitis: evaluation of its presence in the lesion, prosthesis, and blood

Denture stomatitis is a primarily oral disease that affects denture wearers. The presence of Candida albicans in the palatal mucosa, on the internal surface of the maxillary denture, and in the blood of patients with denture stomatitis was evaluated. Although the results did not show C albicans in the bloodstream of patients, a strong relationship between denture stomatitis and Candida sp was confirmed for both the palatal mucosa and maxillary denture.

[The effect of new generation materials used in reconstructive dentistry on the oral cavity environment]

PURPOSE

Loss of teeth impairs the functioning of the stomatognathic system, complicates chewing, interferes with speech, and alters the patient's appearance. Reconstruction of the defects with implants or fixed dentures often proves impossible and removable dentures remain the sole option in such cases. Continuous progress in materials science, as well as growing demands and expectations from both dentists and patients drive the efforts of manufacturers of dental materials towards improved and innovative products. The requirements for prosthetic materials are the same as for medications. The main goal is biological neutrality or, at least, biological tolerance. Polymers and metal alloys are being constantly modified to better suit these demands. T.S.M. Acetal Dental in one of the monomer-free polymers that have recently been introduced to prosthodontics. This product has not yet been the object of extensive clinical and laboratory studies in Poland. Wironit extrahart chromium-cobalt alloy and Vertex R.S. Acrylic have been certified by the Polish Ministry of Health for use in Poland. Therefore, these products were selected for reference purposes in the present study. As the certificate for T.S.M. Acetal Dental is lacking, the product was subjected to experiments in animals and to physicochemical tests.

MATERIAL AND METHODS

The following physicochemical properties were examined: mechanical strength, fatigue limit, abrasiveness, and contact angle. Histopathology of animal material was directed at the reaction of tissues to the prosthetic materials. Adhesion of bacteria and fungi to the materials was examined. The usefulness of acetal resin in prosthetic practice and the biofunctionality of dentures made of the resin were assessed as well.

RESULTS

Mechanical properties of acetal resin seen in the static bending test were clearly inferior to metal alloys. However, the results of dynamic tests were in favor of acetal resin compared with metal alloy. Abrasiveness of acetal resin exceeded that of the metal alloy. The values of contact angle were distinctly lower for resin than for metal which demonstrated values characteristic for hydrophobic materials. Histopathology showed a moderate inflammatory reaction after six weeks of the animal experiment. The reaction was least intense with T.S.M Acetal Dental. However, the inflammatory reaction contained eosinophils, just like in the case of Wironit extrahart, suggesting that both materials have allergic properties. Both materials produced morphological changes in the parotid glands of the animals. The adhesion of bacteria to the materials varied and depended on the bacterial strain. Staphylococcus aureus and Enterococcus hirae strains demonstrated the strongest adhesion to the mechanically polished chromium-cobalt alloy. On the other hand, Escherichia coli adhered strongest to the acrylic resin (10 times the value for acetal resin). Pseudomonas aeruginosa revealed four-fold weaker adhesion to T.S.M. Acetal Dental than to other materials. The adhesion of Candida albicans to acetal resin was three times weaker than to acrylic resin.

In vitro evaluation of artificial ageing on surface properties and early Candida albicans adhesion to prosthetic resins

OBJECTIVE

The aim of this in vitro study was to examine potential changes and influences of prosthetic resin surface properties on Candida albicans adhesion after surface treatment or artificial ageing.

MATERIALS AND METHODS

Standardized specimens of a denture base resin and a veneering composite were prepared, polished, and randomly subjected to different surface roughness treatments or artificial ageing protocols (storage in ethanol or artificial saliva for 7/90 d, thermocycling). Surface roughness (Ra) and surface free energy were determined prior and after each treatment. Specimens were incubated with phosphate buffered saline or whole saliva for 2 h at 37 degrees C, and later with Candida albicans suspension (2.5 h, 37 degrees C). Adherent viable fungi were quantified using a bioluminescence assay.

RESULTS

Artifical ageing did not affect substratum surface roughness, yet slight increases in substratum surface free energy and significant increases in Candida albicans adhesion were observed. Saliva coating marginally influenced Candida albicans adherence to reference and surface treated specimens, yet more pronounced differences in Candida albicans adhesion between the various artificially aged specimens were found.

CONCLUSION

No correlation between substratum surface roughness or surface free energy and Candida albicans adhesion could be established.

The carriage of Candida species on the dorsal surface of the tongue: the correlation with the dental, periodontal and prosthetic status in elderly subjects

OBJECTIVES

To screen the carriage status of Candida species, especially Candida albicans and its genotype in an epidemiological survey and to investigate its correlation with the dental, periodontal and prosthetic status of healthy elderly subjects.

MATERIALS AND METHODS

Microbiological samples were collected from the dorsum of the tongue of 366 subjects, aged 75, and cultured on CHROMagar medium. The carriage status of Candida spp. and the distribution of C. albicans genotypes by a polymerase chain reaction (PCR) method were analysed and compared with the dental, periodontal and prosthetic status of the subjects.

RESULTS

A high carriage rate (68.6%) of Candida spp. and the predominant species of C. albicans (72.1%) were found in this study. The prevalence, density and multi-species of Candida spp. were significantly related to the presence of a dental prosthesis. In C. albicans, genotype A predominated (56.4%) and genotype D showed a higher prevalence (12.5%) than previous reports. When comparing Candida spp. carriage with the oral status, significant positive correlations were found with the presence of any dental prosthesis, missing teeth, the number of retained roots and the percentage of sites showing bleeding on probing (BOP), while significant negative correlations were found with the number of teeth present, sound and filled teeth.

CONCLUSIONS

Candida carriage on the dorsum of the tongue in healthy elderly is significantly associated with the dental, periodontal and prosthetic status, especially the presence of a dental prosthesis. As the complexity of the prosthesis being worn increased, the relative risk of Candida carriage and the numbers and multi-species of Candida increased accordingly.

Relationship between salivary histatin 5 levels and Candida CFU counts in healthy elderly

OBJECTIVES

Few epidemiological studies have confirmed the antifungal activity of histatin 5 in saliva against Candida species. The purpose of this study was to examine the relationship between concentrations of histatin 5 and the number of cultivable Candida in saliva samples from elderly.

METHODS

Whole saliva samples were obtained from 124 elderly people, 65 years or older, living in a rural community. The concentrations of histatin 5 in saliva samples were determined by the enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody. Total colony-forming units (CFUs) were counted on a selective medium for Candida. Multiple linear regression analysis was performed to determine the independent contribution of explanatory variables to Candida CFUs using age, sex, histatin 5 concentration and type of denture prosthesis as independent variables.

RESULTS

Saliva samples from 104 subjects (84%) were candidal colony-positive. The youngest group (65-69 years old) showed significantly smaller Candida CFU counts than those in the older group. The mean Candida CFU count of denture wearers was significantly higher than that of non-denture wearers. Significantly negative associations were found between Candida CFU counts and histatin 5 level in the oldest group (p < 0.05) and in the full-denture wearers (p < 0.01). Multiple linear regression analysis revealed that Candida CFU counts were mostly associated with type of dentures, followed by histatin 5 concentration.

CONCLUSION

Possible activity of histatin 5 against Candida in whole saliva of elderly people was epidemiologically confirmed. The area covered by the prostheses was a strong factor associated with the Candida CFU count.

Oral hygiene and the need for treatment of the dependent institutionalised elderly

OBJECTIVE

To assessing the oral hygiene and treatment needs of a geriatric institution in southern France.

BACKGROUND

For various reasons, the care demand from elderly people is low and difficult to determine, whereas their oral status would need long and complicated treatments.

MATERIALS AND METHODS

From 2003 to 2004, a cross-sectional study of 321 elderly patients was conducted at several geriatric services of Montpellier, France. The clinical evaluation of dental status was recorded together with medical information. Dental and prosthetic hygiene, status of dentures, caries experience, dependence conditions and treatment needs were evaluated.

RESULTS

The prevalence of edentulism was 27%, with no gender difference (23% of the men and 29% of the women). Among them, 16.7% (upper jaw) and 18.1% (lower jaw) were totally edentulous with no denture. The mean number of decayed and missing teeth was 3.7 for men and 2.8 for women and 21.5 for men and 21.0 for women, respectively. The mean number of filled teeth was 0.8 for men and 1.3 for women, with no statistical difference according to gender for the three indexes. Most of the subjects needed prostheses (53%), 45.1% extractions and 30.6% conservative treatments. Only 2.4% did not need any treatment.

CONCLUSION

The prevalence of edentulism was relatively low, while the need for prosthodontic rehabilitation, especially for men, was still very high. The dental hygiene was globally inadequate. This evaluation emphasises the care demand and the need for help in oral hygiene procedures for the dependent institutionalised elderly.

Candida albicans, Staphylococcus aureus and Streptococcus mutans colonization in patients wearing dental prosthesis

BACKGROUND

Denture stomatitis is associated to Candida albicans, different bacteria and other co-factors such as an acid pH, a carbohydrate ingestion increase, different systemic illnesses and pharmacological treatments.

OBJECTIVE

The aim of this study was to determine Candida albicans, Staphylococcus aureus and Streptococcus mutans prevalence in the mucous membrane and prosthesis of patients with and without atrophic denture stomatitis and its relationship with other potential clinical co-factors.

STUDY DESIGN

Saliva was collected from 105 patients (62 female and 43 male) wearing dental prosthesis in order to measure their pH. Oral samples of the mucous membrane and the internal surface of dental prosthesis were taken with sterile cotton to proceed with the microbiological study. The identification of the isolated microorganisms was performed using conventional microbiological methods.

RESULTS

Diabetes and Hypertension were the most frequent systemic illnesses. High carbohydrate ingestion was observed in numerous patients. Atrophic denture stomatitis was reported in 50 patients and the pH average in saliva was of 5.2. The presence of C albicans, S. aureus and S. mutans in the mucous membrane and prosthesis was of 51.4%, 52.4% and 67.6%, respectively. C. albicans was isolated in 66.7% from the prosthesis, whereas S. aureus and S. mutans were isolated in 49.5% of those same prosthesis. C. albicans was isolated in 86% of the patients with atrophic denture stomatitis and S. aureus was isolated in a similar percentage (84% of patients). The isolation of S. mutans was less frequent, and it was observed in 16% of the oral samples of these patients.

CONCLUSIONS

C. albicans, S. aureus and S. mutans frequently colonize the oral mucous of patients wearing dental prosthesis. This illness-bearing condition is more frequent in patients with denture stomatitis, even though dental prosthesis colonization is lower than in the oral mucous.

Microbiological hazard analysis in dental technology laboratories

Dental technicians are trained in a range of skills involved in the fabrication of prostheses used in the mouth and facial region. Items entering the dental laboratory are essentially inert materials which have been in contact with the patient's mouth, saliva, and possibly blood. Appliances leaving the laboratory are then returned to the clinician to be tried/inserted in the patient's mouth. Relatively little attention has been paid to infection control policy within dental laboratories, perhaps due to perceived and/or actual remoteness from patients, lack of appropriate training, and lack of relevant research. More controlled studies are desirable, in order to identify any potentially hazardous procedures, and to make an assessment of risk for these procedures.

Alteration of the coadherence of Candida albicans with oral bacteria by dietary sugars

Interactions between bacterial oral flora and Candida albicans are important in denture plaque formation. This study therefore first aimed to quantify the coadherence of C. albicans and bacteria by the use of a bioluminescent adenosine triphosphate (ATP) assay based on the firefly luciferase-luciferin system. The second aim was to examine the effect of i) dietary sugars (used for preculture) and ii) enzymatic digestion of fungi on the coadherence. When yeast was preincubated in yeast nitrogen base medium (YNB) supplemented with 250 mM glucose, the yeast coadhered with all isolates of Streptoccus mutans and Streptococcus sanguis, and no significant coadhesion was observed with the isolates of Streptococcus sobrinus, Streptococcus salivarius, Lactobacillus and Actinomyces. However, when the yeast was precultured in YNB supplemented with 500 mM galactose, the yeast coadhered with S. salivarius and Actinomyces, which was not observed when the yeast was grown in YNB with glucose. In addition, the coadherence of the yeast with the isolates of S. sanguis was significantly reduced. Enzymatic digestion of yeast and a reverse transcription polymerase chain reaction assay revealed that expression of at least two types of proteinaceous adhesins are involved in these phenomena.

Partial spectrum of microorganisms found in dentures and possible disease implications

While it would appear that denture surfaces alone become colonized by microorganisms, this study showed that the porosity of denture material allows for contamination throughout the entire denture. Further, the numerous opportunistic and pathogenic microorganisms found in this study were unexpected and are known to produce not only substantial oral infections, but also systemic diseases.

[The dynamics of the colonization by the microbial flora of the mouth of the different materials used for dental prosthetics]

Colonization of materials used for making dentures with oral microflora was studied in 12 patients with chronic generalized medium severe periodontitis during remission. Time course of dentures colonization with representatives of oral microflora (S. sanguis, Peptostreptococcus sp., Prevotella oralis) and with bacteria pathogenic for the periodontium (Prevotella melaninogenica, A. naeslundii, Fusobacterium sp.) depends on the material from which the dentures are made. Minimal colonization of bacteria pathogenic for the periodontium was observed on cermet dentures.

Denture hygiene: a review and update

Growth in the aging population has resulted in an increasing number of older persons requiring dentures. The microporous surfaces of an acrylic denture provide a wide range of environments to support microorganisms that can threaten the health of a physically vulnerable patient. The maintenance of denture prostheses is important for the health of patients and to maintain an esthetic, odor-free appliance. Mechanical, chemical, and a combination of mechanical and chemical strategies are available to patients to facilitate denture hygiene. Brushing is an ineffective method of denture disinfection. Household bleach or vinegar are effective as are the commercial, effervescent products sold for denture soaking. A new denture cleaner contains silicone polymer that provides a protective coating for dentures as a final step in the cleaning process. The coating helps to minimize the adhesion of accretions to the denture throughout the day until the next cleaning. Dental professionals must have a current knowledge of denture cleansing strategies in order to maximize the service offered to denture patients.

Retention of oral microorganisms on cobalt-chromium alloy and dental acrylic resin with different surface finishes

STATEMENT OF PROBLEM

The effect of surface finish of dental materials on the subsequent contamination by microorganisms.

PURPOSE

This study compared the retention of Streptococcus oralis, Actinomyces viscosus, and Candida albicans on polished, sandblasted (fine and coarse) and electrobrightened cobalt-chromium alloy and dental acrylic resin to assess in vitro the effect of such techniques on prosthesis contamination.

MATERIAL AND METHODS

Standardized cell suspensions were incubated with test materials for 1 hour at 37 degrees C, after which retained cells were counted by using image analysis (percentage area of a microscopic field covered by cells).

RESULTS

Retention of bacterial cells was substantial (S oralis 12% to 20% and A viscosus 9% to 16%) irrespective of surface finish. Maximal retention was observed on cobalt-chromium alloy that had undergone fine sandblasting and electrobrightening (P < .01). For C albicans, an increase in surface roughness (0.15 to 3.53 microns) resulted in an increase in retention (3% to 9%).

CONCLUSION

Cell size and the type of roughening significantly affected the retention of microorganisms on surfaces. Electrobrightening of cobalt-chromium alloy did not reduce the surface roughness or subsequent cell attachment.

[The use of chlorhexidine as a preventive and therapeutic means of plaque control in the handicapped. Review of the literature and definitive advise for application]

With respect to oral hygiene, most of the handicapped are very dependent. Moreover, it is shown that the higher the dexterity level, the poorer the oral hygiene. It's well documented that the use of Chlorhexidine (CHX) is an essential tool in oral care for the handicapped. The efficacy however, only becomes optimal after thorough plaque and calculus removal. From the literature, it becomes clear that the application of a 1% gel in prefabricated trays is the most efficient. Regarding mouthrinses, it's important to use big volumes in order to reach optimal contact with tooth surfaces. The use of a spray seems very handy but is quiet inefficient; no homogeneous diffusion of CHX can be obtained. The choice of any device for CHX application depends on the handicapping condition and on the knowledge and motivation of educators, and medical care takers. The present article summarizes the dental literature on the use of CHX in handicapped. An advice for well indicated use of CHX is proposed.

Effect of treatment concentration on lipopolysaccharide affinity for two alloys

OBJECTIVE

This study compared gram-negative bacterial lipopolysaccharide (LPS) adherence to and elution from a Type III gold and a Ni-Cr-Be alloy using Escherichia coli LPS.

METHOD

One-half of the specimens of each alloy were pre-treated with 500 micrograms non-radiolabeled E. coli LPS for 24 h at 37 degrees C. All disks were then incubated with 0.15, 15 or 150 micrograms radiolabeled E. coli LPS for 24 h at 37 degrees C. To evaluate radiolabeled LPS elution, specimens were transferred to LPS-free water and incubated for 24 h at 37 degrees C. The elution scheme, which consisted of 24 h incubations and subsequent transfer to new LPS-free water, continued for up to 96 h total elution. Radiolabeled LPS adherence and elution was determined through liquid scintillation spectrometry. Control disks not treated with LPS were evaluated throughout the study with an enzymatic assay to ensure that extraneous LPS contamination did not occur. A multifactor ANOVA (p = 0.05) was used to evaluate differences in adherence to alloy specimens based upon alloy type, pretreatment status and [3H]LPS concentration. A repeated measures analysis ANOVA (p = 0.05) was used to evaluate differences in elution patterns among groups over time. Least square means were compared in case of significant effects.

RESULTS

Toxin uptake at each treatment concentration was significantly different from the other treatment concentrations. In addition, significantly greater amounts of [3H]LPS eluted from the non-pretreated Ni-Cr-Be alloy following the 0.15 and 15 micrograms radiolabeled [3H]LPS treatment, whereas no difference in elution was found among experimental groups following the 150 micrograms [3H]LPS treatment.

SIGNIFICANCE

E. coli LPS, an LPS type representative of enteric bacteria common to the gingival sulcus, has differing affinities for the alloys. This affinity difference could influence periodontal inflammatory processes, thereby resulting in differing tissue responses adjacent to dental restorations fabricated from these materials. The interaction of other LPS types with these alloys could differ.

Adherence of Candida albicans to experimental denture soft lining materials

STATEMENT OF PROBLEM

Colonization of denture soft lining materials by Candida albicans can result in clinical problems. Two experimental silicone soft lining materials have been developed and demonstrate good physical properties.

PURPOSE OF STUDY

The aim of this study was to determine the extent of candidal adherence to these materials compared with a commercially available soft lining material and an acrylic resin denture base.

MATERIAL AND METHODS

The experimental materials were constructed in a stainless-steel mold, and their surface energies were determined with a dynamic contact angle analyzer. The adherence of three strains of C. albicans was determined with an in vitro assay. In addition, one test strain was used to determine the effect on adherence of precoating the materials with whole saliva.

RESULTS

Adhesion to all materials was strain variable, with the lowest adherence recorded for the two experimental materials. Decreased adherence was also apparent after precoating the materials with saliva. Correlation between surface energy of the material and the degree of candidal adhesion was seen for one strain, but no correlation was seen for the other two strains.

CONCLUSION

Adherence of C. albicans to the two experimental silicone soft lining materials was significantly less than that for an acrylic resin denture base and a commercially available soft lining material.

In vivo plaque formation on cast ceramic (Dicor) and conventional ceramic

This study compared plaque accumulation on glazed and nonglazed metal ceramic porcelain surfaces with shaded and nonshaded Dicor cast ceramic surfaces. Plaque accumulation on natural teeth was also measured at 4, 12, 24, and 48 hours. Bacterial cultures were prepared from each sample to establish the aerobic and anaerobic charge. Plaque accumulation between 12 and 24 hours was measured on different materials. No significant differences were discovered between the plaque-retaining capacities of metal ceramic porcelain and Dicor ceramic surfaces. There was less plaque accumulation on glazed surfaces than on nonglazed surfaces.

A clinically viable index for quantifying denture plaque

A denture plaque index using the dye disclosing method was evaluated in 24 patients with Type II denture stomatitis and 17 control subjects with healthy palatal mucosa. Patients with denture stomatitis had statistically significantly higher plaque scores than did controls, indicating a quantitative increase in denture plaque in patients with denture stomatitis. When this plaque index was tested by two examiners for intraexaminer and interexaminer reproducibility, it yielded a 92% to 96% reproducibility. The plaque index used in this study seems to satisfy the criteria for an ideal clinical index: It is simple, reliable, reproducible, and economical and can be carried out in the shortest possible time in a clinical setting.

Methicillin-resistant Staphylococcus aureus and Candida albicans on denture surfaces

Infectious diseases caused by methicillin-resistant Staphylococcus aureus, MRSA, and Candida albicans are often serious in compromised hosts. We enumerated MRSA and C. albicans on denture surfaces and in saliva samples from 29 adults. Staphylococcus species, MRSA, and methicillin-resistant Staphylococcus epidermidis, MRSE, were detected on 17, 3, and 1 of the 29 denture surfaces, respectively. C. albicans were detected on 22 denture surfaces. All saliva samples from patients whose dentures carried Staphylococcus species and C. albicans were also found to contain both microorganisms. Adherence of isolated 3H labeled cells of MRSA and C. albicans to resin beads and saliva-coated resin beads was examined. Cells of both microorganisms adhered in significantly higher numbers to saliva-coated resin beads than to resin beads. The hydrophobicity of the MRSA isolated from denture surfaces varied from strain to strain; that of C. albicans strains was moderately high. The zeta potentials of MRSA isolates and of C. albicans isolates determined in KCI buffer were significantly low. The potential of the resin beads decreased after treatment with saliva. Two out of 5 MRSA strains were found to be inhibited in growth by oral Streptococcus, Actinomyces, and gram-negative bacterial strains, suggesting that some oral bacterial species play a role in inhibiting the colonization of Staphylococcus species. No isolates of C. albicans were inhibited in their growth by any of the oral bacteria tested. Isolates of MRSA and C. albicans coaggregated with Porphyromonas gingivalis and Fusobacterium nucleatum strains. Using denture cleaners every night for 2 weeks did not reduce numbers of Staphylococcus species or C. albicans organisms in saliva.

A method for scoring denture plaque

Many studies have reported on the comparative efficiency of denture cleaning materials in their ability to remove deposits from dentures, but because of the variety of scoring methods used it is often difficult to make direct comparisons between materials. It is important that any measurements obtained should not only be accurate, reliable and reproducible but that inter-examiner error should be kept to a minimum. In this work three operators were asked to score 'blind' the total amount of disclosed plaque on a whole denture using a 0-10 scale. The overall conclusions of this test was that of poor inter-examiner agreement. A second test was therefore undertaken at a later date using the same three operators and protocol but on this occasion each surface of the denture was evaluated by reference to a series of standard reference dentures painted to simulate plaque scores in the 0-10 range. This test showed there to be no significant difference in the plaque scores recorded by the three operators and that the plaque scores recorded on the polished surfaces were significantly lower than those on the teeth and fitting surfaces (F = 10.55, P < 0.001).

In-depth disinfection of acrylic resins

This study demonstrated that bacteria penetrate three kinds of dental acrylic resin after a short time period. Samples of acrylic resin were contaminated with a variety of bacteria and were then placed in three different disinfecting solutions as directed by the manufacturers. After the specific dilution and immersion time, cultures were made from the resin samples. The only effective disinfectant was a 0.525% solution of sodium hypochlorite at a 10-minute immersion. It disinfected not only the surfaces but also the bacteria that penetrated the surfaces to a depth of 3 mm.