[Adhesion of Streptococcus mutans to removable denture crowns].

OBJECTIVE: To determine adhesion of Streptococcus mutans (S. mutans) to different kinds of removable denture crowns for the purpose of minimizing influence of removable denture on oral environment. METHODS: Three kinds of removable denture crowns (single color synthetic resin teeth, alloy pin porcelain tooth and minute color synthetic resin teeth) were adsorbed S. mutans for 24 h in sterile saliva, The adhered bacteria were counted by means of sonic oscillation and bacteria coating. RESULTS: Highest level of adhesion was found on ,the single color synthetic resin teeth was adsorbed mostly, followed by alloy pin porcelain teeth. Minute color synthetic resin teeth had far less adhesion than the others (P<0.01). CONCLUSION: Minute color synthetic resin teeth have less adhesion of S. mutans, which may be associated with their lower level of surface free energy.

Occurrence, isolation and differentiation of Candida spp. and prevalence of variables associated to chronic atrophic candidiasis.

The purpose of this study was to survey the frequency of Candida spp. in patients with chronic atrophic candidiasis (CAC), to differentiate Candida species and to assess the prevalence of certain infection-associated variables to this disease. Patients with CAC and wearing partial or complete dentures were recruited. Data were obtained by means of a questionnaire with details involving identification of the subject, demographic characteristics, behaviour and medical history, clinical and mycological evaluation and identification of yeast. The sample collection was carried out in the palate or palate and tongue of the subjects using sterilised swabs. Data were submitted to statistical analyses using Fischer's test. Forty-three (53%) cases of CAC showed the presence of Candida albicans. Females (75.2%) wearing complete dentures (60.1%) for more than 10 years (58%) were risk factors to CAC development. It could be concluded that: (a) the results did not confirm a significant difference among patients with CAC concerning the presence or absence of Candida spp.; (b) the occurrence of Candida was negatively related to important factors associated to this opportunistic infection; and (c) mycological findings did not indicate that the variables investigated have a significant effect on oral infections by C. albicans or other Candida species.

SEM analysis of the in situ early bacterial colonization on two novel feldspathic ceramics submitted to different types of glazing.

AIM: The aim of this study was to evaluate in situ, the early bacterial colonization on feldspar-ceramics submitted to different glazing. METHODS AND MATERIALS: Fourteen standardized disc specimens (diameter: 5 mm, thickness: 1.5 mm) of each of two micro-particulate feldspathic ceramics (VM7 and VM13, Vita) were produced according to manufacturers' specifications for a total of 28 specimens (24 for the analysis of biofilm and 4 for topographic analysis analyzing the ceramic surfaces). Specimens from each type of ceramic were submitted to two different glazing methods composing four groups: VM7 glazed using glazing liquid Vita Akzent 25 (G1) and glaze firing (G2), VM13 glazed using glazing liquid (G3) and glaze firing (G4). Six individuals (n=6) wore oral appliances with four ceramic specimens, fixed on the buccal face of the appliances. After 8 hours, each sample was evaluated for the presence (1) or absence (0) of bacterial colonization under a scanning electron microscope (SEM) on five randomly selected fields. The value for each sample was cumulative of the results observed in the fields. One sample from each group was evaluated under a SEM to verify the topographic pattern. RESULTS: There was no difference with regard to bacterial colonization between the feldspar-ceramics and between the glazing types (Kruskal-Wallis non-parametric test). CONCLUSION: Feldspar-ceramics submitted to firing or glaze firing with Vita Akzent 25 present a similar condition for in situ bacterial colonization. The similar topographic pattern of the ceramic surfaces seems to have influenced the bacterial colonization.

Malodour in denture wearers: an ill-defined problem.

Denture plaque has not been studied to the same extent as dental plaque, and although there are many similarities in microbial composition, there are some significant differences. Denture-induced stomatitis is associated with poor denture hygiene, a more acidogenic plaque and the presence of Candida albicans. Obligate Gram-negative anaerobic micro-organisms, although present in denture plaque, have rarely been specifically investigated. Opportunist pathogens including coliforms and staphylococci have been isolated from dentures. Teeth adjacent to partial dentures are more susceptible to caries and periodontal diseases, perhaps due to an increased plaque buildup at the prosthesis/tooth interface. Little work has been published on malodour associated with dentures. The inert material provides a substratum for the plaque biofilm, which encompasses a range of odour-producing species. The microbiology of the tongue in denture wearers has not been specifically studied. Thus the nature, origin and extent of malodour in denture wearers is ill-defined, but many species capable of producing malodorous compounds are present. The wide age and health range presented by denture wearers further confounds investigation. There is a need for further work in the area, both for cosmetic- and health-associated reasons in the increasing elderly population.

Control of denture plaque and mucosal inflammation in denture wearers.

The aims of this study were to collect data about the popular methods and materials used for cleaning dentures among complete and partial denture wearers in Jordan and to discuss the relationship between denture base plaque and mucosal inflammation under dentures. A questionnaire consisting of six questions regarding denture hygiene practices and cleaning products was completed by 321 patients who attended two prosthodontic clinics for replacement or adjustment of their dentures. Following careful oral examination and examination of dentures, the relationship between denture hygiene and inflammation under the denture base was investigated. In this study there were 615 dentures and 321 patients. The mean age of patients was 65 years and it ranged from 18 to 100 years (s.d. = 10.1). The mean age of their dentures was 7.3 years (s.d. = 5.6) ranging from one to 27 years. The most popular method of cleaning dentures was brushing. Ninety-four (29 per cent) of the denture wearers had denture stomatitis. There was a statistically significant relationship between poor denture hygiene and denture stomatitis (P = 0.0001). There was also a significant relationship between continuous wearing of the dentures, day and night, and denture stomatitis (P < 0.0001). The presence of bacterial and yeast plaque on the fitting surface of the denture base appeared to be of critical importance for development and maintenance of denture stomatitis. It is necessary, therefore, that dentists should give instructions to denture wearers on how to clean their denture surfaces properly so as to maintain good hygiene and prevent denture stomatitis.

[Microbiological validation of the choice of basic plastic for removable dentures]. / Mikrobiologicheskoe obosnovanie vybora bazisnoi plastmassy s"emnykh zubnykh protezov.

Adhesion of obligate and facultative anaerobic bacteria, favoring the development of oral inflammatory diseases, including the cariesogenic and periodontogenic bacteria and Candida albicans fungi, isolated from patients with periodontitis, to 13 basic materials used in removable denture making, was studied. The adhesion of all bacteria (Streptococcus sanguis, Prevotella melangogenica, Fusobacterium nucleatum, Corynebacterium xerosis) and fungi to hot polymerization basic materials was the maximum. The most perspective basic plastic for clinical use (preserving intact oral microbiocenosis and preventing stomatitis induced by denture wearing) are cold polymerization materials, such as Redont-03, Dentoplast Breden, Leocryl, and UHF polymerization materials Acron GC, AKR-MV, and Etakril-02.

Denture-related stomatitis: identification of aetiological and predisposing factors - a large cohort.

The aim of this study was to identify and characterize aetiological and predisposing factors in denture-related stomatitis (DRS), by means of a case-control, transversal study, in a large cohort of 140 persons wearing removable maxillary polymethylamethacrylate prostheses. Data were obtained by (1) a questionnaire that included the identification of the subject, demographic and social data, medical history and behaviour; (2) intra-oral examination; (3) evaluation of the prosthesis; (4) microbiological examination; (5) yeast identification and analyses using Epi-info and the chi-square test. Results showed significant associations between DRS and yeasts, gender, age and alcohol consumption. We also found a significant relationship between the presence of yeasts and hyposalivation and decreased salivary pH. We found a highly significant difference between groups with and without DRS concerning the presence or absence of yeasts, regardless of the sample origin. Most cases of DRS showed the presence of Candida albicans. The results confirm a highly significant difference between groups with and without DRS concerning the presence or absence of yeasts.

[The study of precedent subgingival flora colonization on four kinds of crown and bridge restorative materials].

The purpose of this in vitro study was to investigate the effects of microbial colonization on different crown or fixed bridge-used restorative materials and discuss the standards for evaluating those materials microscopically. Four kinds of restorative materials such as SDA-II type medium alloy, ceramic-fused-to-metal material, heat cure composite resin for crown restoration, Plat castable ceramics and four species of precedent subgingival flora (A. viscosus, F. nucleterm, C. ochracea, S. sanguis) were used. The material specimen had been continuously anaerobic cultured with the experimental bacterial fluid for 3, 7 and 14 days respectively, then the OD values of the specimenwashing fluid which could stand for the biomass of colonized bacteria on the surfaces of materials were measured. The results indicated that the quantity of precedent subgingival flora colonization on the surfaces of different restorative materials varied among different species of bacteria, which might concern with the surface structure, composition, property of anticorrosion and antisoluability of those materials.

Microleakage of oral microflora for porcelain and some porcelain repair materials--in vitro study.

Repairing porcelain fractures has become of interest to the dentist. The intra oral fracture of metal-ceramic restorations may be due to inadequate metal support, excessive porcelain thickness, technical flaws, and occlusal forces. Various techniques for intra oral porcelain repair have been suggested. The resin-porcelain junction has been in question since the advent of the porcelain veneer for cast metal restorations. To enhance this, several intermediary products and techniques have been developed to increase the chemical bond between the fractured porcelain and the repair materials. Clinical procedures for porcelain repair has required roughening of porcelain surface with a rotary abrasives, application of silane followed by composite to replace the contour of the restoration (2, 13, 14). Laboratory data suggested that the strong bond of the repair materials was developed.

Histobacteriology and pulp reactions to long-term dental restorations.

The prevention of degeneration and necrosis of the endodont is one of the main goals of dental treatment. Kerschbaum and Voss (1979, 1981) described that 15% of teeth showed negative results to sensitivity testing 10 years after crown preparation. Pulpal responses to dental treatment depend on many factors including thermal injury, transsection of the odontoblastic process, vibration, desiccation of dentin, pulp exposure, smear layer, remaining dentin thickness and used materials. The knowledge concerning endodontic reactions in short and medium term observation is mainly based on research by Klötzer and Langeland. Histological assessment of reactions is a well accepted method for biocompatibility testing (i.e. ISO/TR 7405). It is consistent to apply its principles to the evaluation of endodontic reactions of teeth with long term restorations. As pulpal injury is furthermore due to microleakage between filling material and the wall of the cavity the analysis of infected dentin tubules seems to be important. A consideration of the location of the tubules and of the severity of the invasion is necessary. Using a classification (grade 1-6) comprising the parameters of degenerative and regenerative reactions and bacterial invasion, 24 teeth restored with different types of fixed prosthodontic restorations were investigated. The restorations were between 0-6, 7-12 and 13-18 years in situ. Serial sections (5 microns) were stained with haematoxylin-eosin, azan, according to Goldner and J. Hopkins. 22 of 24 teeth showed typical degenerative reactions. Negative sensitivity testing occurred in teeth with no pain and no or partial necrosis. The histobacteriological assessment showed bacterial invasion of the dentin tubules of 21 teeth. From this investigation it was concluded that the proposed classification shows sufficient sensitivity for the evaluation of progressive endodontic changes of long-term restored teeth. Furthermore it was shown that bacterial invasion must be considered as a possible co-factor for the described degenerative character of the pulpal tissue.

Early colonization of dental implants by putative periodontal pathogens in partially edentulous patients.

There is limited scientific information available on the early colonization of the peri-implant pockets in partially edentulous individuals. Knowledge about this process is one step in better understanding the etiology and pathogenesis of peri-implantitis. In this study, the early colonization of the peri-implant pockets by putative periodontal pathogens was studied in 20 partially edentulous individuals using anaerobic culture techniques. At baseline, the presence and levels of putative periodontal pathogens in the microflora of periodontal pockets and saliva were established. Immediately after loading of the titanium implants and after 6 and 12 months the presence and levels of selected putative periodontal pathogens were determined in periodontal and peri-implant pockets. A second aim was to detect bacterial contamination of the implant site and the inside of the implant. At baseline, the most frequently isolated species from the periodontal pockets were Fusobacterium nucleatum, Prevotella intermedia and Peptostreptococcus micros. Bacteroides forsythus, Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis were isolated from 9, 2 and 3 patients respectively. Six months after placing of the bridges, the majority of the implant sites had detectable levels of most periodontal bacterial species with the exception of A. actinomycetemcomitans which could not be isolated from any of the peri-implant samples during the experimental period, although 2 patients had this organism at baseline. In 2 patients with detectable subgingival P. gingivalis at baseline this species was found after 12 months in the peri-implant sites. One of these patients lost 2 implants which was associated with a high proportion of P. gingivalis in the peri-implant pockets. A second patient developed 2 fistulas around 2 implants at 8 months and this event was also associated with the presence of P. gingivalis. It is concluded that proper periodontal infection control before installment of dental implants in partially edentulous patients may prevent early bacterial complications.

Salivary cytokine profiles in the immunocompetent individual with Candida-associated denture stomatitis.

Cell-mediated immunity conferred by CD4+ T helper cells is considered the predominant host defense against mucosal Candida infections, with Thelper (Th1)-type responses associated with resistance to infection and Th2-type responses associated with susceptibility to infection. Oropharyngeal candidiasis, the most common oral opportunistic infection in HIV-infected persons, is associated with a Th2-type cytokine profile in saliva. To obtain more direct evidence for a role of salivary cytokines in susceptibility to oropharyngeal candidiasis during immunosuppression, we evaluated Th1/Th2-type cytokines in the saliva of those with denture stomatitis, a form of oropharyngeal candidiasis not related to immunosuppression. Results showed that HIV-negative denture wearers with and without denture stomatitis demonstrated a mixed Th1/Th2 cytokine profile with no significant differences found between the groups. These results suggest that a local Th cytokine dichotomy in saliva is not associated with susceptibility to denture stomatitis in immunocompetent persons.