Adhesion and biofilm formation by periodontopathogenic bacteria on different commercial brackets.

AIM: To compare early bacterial adhesion and biofilm formation of common and uncommon periodontal pathogens on a variety of commercial brackets in vitro. MATERIALS AND METHODS: In vitro adhesion and biofilm formation of 4 bacterial strains on 15 different commercial brackets, in standard culture mediums with and without addition of either serum or human saliva was evaluated by quantitative real time PCR after extraction of bacterial DNA. RESULTS: Materials significantly influenced bacterial adhesiveness in a species-specific way. Titanium and gold brackets constantly yielded the lowest values with all tested bacteria and in all tested conditions. Bracket materials and medium of growth significantly influenced biofilm formation. CONCLUSION: Materials and environmental conditions significantly influence biofilm formation by periodontal pathogens at the surface of brackets. Whenever possible brackets should be kept far from the gingival margin and if this is not possible, brackets made of gold, titanium, and ceramic should be preferentially used.

Combination therapy including serratiopeptidase improves outcomes of mechanical-antibiotic treatment of periimplantitis.

This study was designed as a retrospective analysis of clinical outcomes of cases of periimplantitis treated by mechanical debridement and the administration of antibiotics combined or not with the administration of either the proteolytic enzyme serratiopeptidase (SPEP) or non-steroidal anti-inflammatory drugs (NSAIDs). Clinical charts of 544 partially edentulous patients treated for periimplantitis between June 1996 and December 2010 were analyzed to obtain clinical data of the affected implants just before the beginning of treatment and 12 months later to evaluate the outcomes of combined mechanical antibiotic treatment alone or in combination with the co-administration of the anti-inflammatory SPEP or NSAIDs. The comparative analysis revealed that therapeutic outcomes were significantly different in the three groups. Failure rate in the group that received SPEP (6 percent) was significantly lower compared to the group that received NSAIDS (16.9 percent; P less than 0.01) and to the group that received no anti-inflammatory therapy (18.9 percent; P less than 0.01). Treatment including SPEP was associated with significantly better healing also when successful treatments alone were considered. The data reported in this paper strongly support the hypothesis that SPEP is a valid addition to protocols for the combined therapy of peri-implantitis. In fact, it allows to enhance success rates significantly and also favors better tissue repair around successfully treated implants as compared to other regimens.

Adhesion and biofilm formation by oral streptococci on different commercial brackets.

AIM: To compare early bacterial adhesion and biofilm formation in vitro by different oral streptococci on a variety of commercial brackets. METHODS: Adhesion and biofilm formation in vitro of 6 Streptococcus spp. on 15 different commercial brackets, in standard culture medium and in human saliva were evaluated by the MTT reduction assay. RESULTS: Significant differences were evidenced in both early adhesion and biofilm formation among the studied brackets and between the two conditions of growth. Gold brackets resulted less prone to colonisation compared to composite brackets. The growth rates of the tested species on the different tested materials were significantly different. CONCLUSION: The adopted experimental plan, dissecting the two phases of plaque formation on different brackets in different conditions, showed that composite brackets are more susceptible to adhesion and colonisation by streptococci, while the remaining tested brackets did not show differences that could be clinically relevant. Data suggest that different personal behaviours affecting the oral environment could significantly affect colonisation of brackets by oral streptococci.

In vitro adhesion of commensal and pathogenic bacteria to commercial titanium implants with different surfaces.

Although dental implants have undergone impressive evolution in recent years, periimplantitis still remains a relevant problem and information on the susceptibility of commercial implants to bacterial colonization is insufficient. This work evaluated the susceptibility of different commercial implants to bacterial colonization, to identify key features for good performances. Twenty-four implants, produced with different technologies, were colonized with 9 bacterial strains following pre-conditioning with culture medium, or saliva or serum proteins and adherent bacteria were enumerated by Real Time quantitative PCR. The studied implants differed significantly for susceptibility to bacterial adhesion. Pre-conditioning of surfaces affected adhesion assays in a species specific manner. Although surface topography influenced bacterial adhesiveness, implants produced by different manufacturers with comparable technologies showed great variability of results. These data demonstrate that susceptibility of implants to bacterial colonization is influenced by productive technologies (in a surface topography proportional manner) and by the productive environment. In choosing an implant the clinician should rely upon specific experimental studies, because surface characteristics alone cannot predict susceptibility to colonization by pathogenic bacteria. Tests should include assays performed in the medium of culture and in the presence of serum proteins.

Influence of oral conditions on colonization by highly toxigenic Staphylococcus aureus strains.

OBJECTIVES: As the oral cavity is regarded as a relevant site for Staphylococcus aureus colonization and interhuman transmission, this study aimed to investigate whether different oral conditions influence the rates of S. aureus oral carriage and genetic characters of S. aureus isolates. SUBJECTS AND METHODS: Staphylococcus aureus was searched in samples collected from cheek, gingival margin, and anterior nares of 45 healthy subjects, 27 periodontitis affected subjects, and 29 subjects with fixed prosthetic restorations. Isolates were screened for 17 genetic determinants, and Partial Least Square Discriminant Analysis was performed to evaluate whether specific characters correlated with oral condition or site of isolation. RESULTS: The three subject groups showed comparable nasal carriage rates but, both the periodontitis and prosthetic restoration groups showed significantly higher oral carriage rates, as compared to healthy subjects (P = 0.01 and 0.02, respectively). Moreover, periodontitis affected subjects hosted strains possessing a distinct genotypic and phenotypic background, characterized by the presence of a larger number of exotoxins encoding genes. CONCLUSIONS: These data confirm that the oral cavity is an important site of S. aureus colonization and demonstrate that conditions modifying the oral environment, as the presence of periodontitis and of fixed prosthetic restorations, promote S. aureus carriage and may favor the spread of more pathogenic strains.

Effectiveness of a glutaraldehyde formulation in decontamination of dental unit water systems.

AIM: Dental-medical devices may transmit infections caused by bacteria that are usually found in water distribution systems, and which are difficult to treat and control. High bacterial contamination in the water systems of dental units is due to the presence of biofilm inside the pipes. Our study evaluated the efficacy of glutaraldehyde formulated with quarternary ammonium salts (Sanicide T4) examined in a previous study, employing a series of assays to confirm or otherwise the results obtained previously. METHODS: A purification protocol for the dental unit water system, together with a protocol for daily maintenance treatment, were tested on two dental units (in the Departments of Conservative and Prosthetic Dentistry) taking specimens from the turbine, micro-engine and air-water gun. The chemical substance, at a concentration of 20 cc per litre of water, was allowed to act when the department closed, for a total of 15 days. The Sanicide T4 was handled with protective gloves and the dental units were fitted with two safety devices to avoid accidental ingestion. RESULTS: Laboratory results enabled us to compare values for bacterial load at 36 degrees C and at 22 degrees C and for Pseudomonas aeruginosa, before and after applying the test protocol. Data obtained are satisfactory except for Pseudo-monas in the fountain in the Department of Conservative Dentistry; the value was in any case below the safety level set by the American Dental Association, confirming the results obtained in our previous study. CONCLUSIONS: The two protocols may now be considered an excellent solution to control the development of biofilm. Should the product be found to be effective for a longer period of use, each dental unit should be provided with: an anti-reflux valve to stop accidental ingestion of disinfectant; a hydraulic mechanism to pump the product to the handpieces and other water supply devices; possibility of discriminating the use of the public water system from the use of that in the disinfectant circuit; an automatic mechanism whereby the disinfectant can be flushed out with drinking water every morning.

[Set up of in vitro methods able to detect the safety of astringent liquids]. / Messa a punto di metodi in vitro per la valutazione dell'innocuità dei liquidi astringenti.

AIM: Most of dental operators agree about a gengival retraction impregnated cord in order to obtain an accurate and overwide dental impression. Hemostatic agents allow the formation of the primary coagulum that determines/causes the retraction of gum connective. Sometimes these astringent liquids cause local inflammation reaction as reported in literature. Aim of this work was the evaluation of the cytotoxic and inflammatory action of the most common astringent liquid on human gum primary cells by in vitro tests. METHODS: For this purpose primary cultures of normal human oral keratinocytes were established, following used either as monolayer or as reconstituted model. All dental preparations were dissolved in CEC medium, diluted to the designed concentrations and applied to the cultured cells. The cytotoxicity was determined by using MTT test, able to evaluate the succinate dehydrogenase activity and therefore the cell viability. Control cultures were treated with CED alone, whereas sodium dodecyl sulphate (SDS) was used as a positive control. Furthermore, the inflammatory response, determined by measuring TNF-alpha and IFN-gamma release, was evaluated on a reconstituted multilayer human oral epidermis model. RESULTS: All agents tested showed a dose-dependent increase in the cytotoxicity to normal human gingival keratinocytes over the dose range examined. In particular the results obtained suggest the higher toxicity of the Astringedent X compound. CONCLUSION: The results obtained from the present studies not only provide useful estimates of relative toxicities of these preparations to human oral mucose, but also can be useful as a standard for cytotoxic and inflammatory assessment of newly developed dental preparations to be topically applied to the oral mucosa. It is important to note, however, that the interpolation of these findings to in vivo conditions remains to be done.

[Environmental monitoring of infective risks in Italian dental offices]. / Monitoraggio ambientale dei rischi infettivi legati all'assistenza odontoiatrica.

BACKGROUND: Bacterial contamination in dental offices plays a primary role in the evaluation of infective risks for patients and dental personnel. The aim of the research was to study bacterial contamination in eight Italian dental offices by investigating the water of dental units, the air and certain surfaces (push-button panel and instrument cabinet) in order to evaluate potential risks in dental practices. METHODS: The water underwent a microbiological test as specified by Italian law (DPR 236/88). The water was sampled from the hoses and air/water syringes of twenty dental units. The microbiological analysis of the air was performed using sedimentation plates to evaluate microbial fall-out. The microbiological analysis of the surfaces was performed using membrane filters to evaluate microbial accumulation. RESULTS: The research showed bacteriological contamination of the dental unit water in all the dental offices. During the working activity total bacteriological counts in the air fall-out were fairly high and the surfaces examined showed some widespread bacterial contamination in dental practices. The results of this study show the importance of routine monitoring of microbial contamination of dental offices and, in case of contamination, the need to apply disinfection treatments for the waterlines and preventive measures for the aerosol reduction. CONCLUSIONS: Our research was used to work out a program for the prevention of environmental contamination in dental offices.

[Decontamination of dental unit waterlines using disinfectants and filters]. / Decontaminazione del sistema idrico del riunito mediante disinfezione e filtrazione.

Bacterial contamination of the dental unit water system can become a health problem for patients, particularly if they are immunodepressed. The present study has had the purpose of evaluating the effectiveness of methods of chemical decontamination using different disinfectants (peracetic acid, hydrogen peroxide, silver salts, chloramine T, glutaraldehyde T4) and methods of physical decontamination using synthetic membranes for the filtration of water. A preliminary removal procedure of the biofilm present in the waterline has been followed in a dental unit prepared on purpose for the research; subsequently different 2-week long maintenance procedures were applied using disinfectants injected by a pump and finally the bacterial contamination of the water flowing from the waterline was evaluated. The physical decontamination was performed using 0.22 mm membrane filters, which have been installed also in another dental unit, and the filtered water was analyzed to detect bacterial contamination. The preliminary procedure of biofilm removal succeeded obtaining germ-free water. Among the disinfectants used for the maintenance of the water quality only glutaraldehyde T4 was able to reduce the bacterial contamination under the limit suggested by the ADA. The membrane filter system was not able to purify the water, but when a disinfectant (peracetic acid) was used in the last part of the waterline good results were obtained. At present no decontamination system of dental waterline is available, and glutaraldehyde T4 seems to be the best disinfectant only if integrated with periodic biofilm removal for the maintenance of the water quality.

Evaluation of the clastogenic activity of some resins used in the prosthodontic field.

BACKGROUND: Dental materials, in particular resins used in prosthetic, orthodontic, conservative and gnathological dentistry, are frequently in long-term contact with the tissues of the mouth, and the chronic exposure to these products of a significant proportion of the population means that the release of genotoxic substances by dental resins must be evaluated. METHODS: For this purpose, ten methyl metacrylate-based resins, both cold- and hot-polymerising and all of frequent use in clinical practice, were prepared following the indications in Standard UNI 9582-2 now included in Standard ISO 10993. Genotoxicity was evaluated through the Tradescantia/micronuclei test. RESULTS: By using the Tradescantia/micronuclei test, which detects aberrant chromosomes by detecting micronuclei in flower tetrads, nine resins were found not to the positive; one resin caused a significant increase in the frequency of micronuclei compared to negative controls. CONCLUSIONS: The results of the Tradescantia/micronuclei test, together with the results of tests cytotoxicity and the Ames and Allium cepa tests performed in previous research, indicate a need for further analyses of these resins for dental use, through other in vivo and in vitro tests, in order to achieve certainty over the risk connected with their use in human populations.

[Dose and exposure reduction in endodontic radiology through the use of new filters]. / Riduzione della dose di esposizione in radiologia endodontica tramite l'utilizzo di nuovi filtri.

In this study the authors discuss parameters which influence the emission spectrum of x-rays and criteria that have an influence on their distribution (anode current, tension), and they draw attention to the materials most frequently used for filter construction-niobium in particular. The authors conducted a clinical study to verify whether the use of a niobium filter mounted on an x-ray machine would decrease the amount of exposure to the patient and give a higher quality image as well, because of decreased radium diffusion which consequently diminishes the risk to the operators.