Identification of streptococcus mitis group species by RFLP of the PCR-amplified 16S-23S rDNA intergenic spacer.

Mitis group streptococci are pioneer colonizers of tooth surfaces and are implicated in various pathologies. Thus, accurate identification of oral mitis group strains would be valuable for studies of plaque ecology and dental caries and for diagnostic use in endocarditis or sepsis patients. The aim of this study was to evaluate the usefulness of PCR-RFLP analysis of the 16S-23S intergenic spacer for differentiating and identifying streptococcus mitis group species. The 16S-23S rDNA spacer regions of 27 type and reference Streptococcus strains, representing 8 species, were studied by PCR-mediated amplification by using oligonucleotide primers FGPS 1490-72 and FGPL 132'-38. PCR products were digested, independently, with 14 restriction enzymes. Only AluI, MboI, CfoI, HinfI and MaeII distinguished some species, particularly AluI and CfoI, but not all the species. Eight clusters were clearly generated, corresponding to currently recognized species, but only with the addition of five ITS restriction patterns, generated by AluI + MboI + CfoI + HinfI + MaeII, then clustered by UPGMA, on a distance consensus matrix. The combination of these five ITS RFLP tests allowed a relatively conclusive genomic group differentiation of mitis group species. Despite this observation, more strains of each species will need to be analyzed, particularly clinical isolates, before arriving at general conclusions about the utility of ITS restrictions for identification of strains at the species level. An ITS PCR-RFLP-based identifying method for streptococcus mitis group species would provide significant advantages over other molecular taxonomic methods which require DNA extraction and DNA-DNA hybridization.

Antimicrobial activity of Ca(OH)2 dental cements: an in vitro study.

The effect of five commercial calcium hydroxide root canal medications (XR-SPAD, Calcicur, Hy-cal, Root-cal, Hypo-cal) and two calcium hydroxide mixtures (with water or glycerin) on the growth of (a) three anaerobic bacteria associated with endodontic infections; and (b) saliva bacterial strains was determined using the agar diffusion inhibitory test. Statistically significant zones of bacterial growth inhibition for all the bacteria tested were observed. Calcium hydroxide mixed with glycerin showed the largest zones of bacterial inhibition, whereas Root-cal was the least active. These results underline the necessity to evaluate the antibacterial potential of endodontic medications against the different bacterial strains commonly isolated from infected root canals.

Surface free energy and bacterial retention to saliva-coated dental implant materials--an in vitro study.

The aim of the present investigation was to compare the in vitro bacterial retention on saliva-coated implant materials (pure titanium grade 2 (cp-Ti) and a titanium alloy (Ti-6Al-4V) surfaces), presenting similar surface roughness, and to assess the influence of physico-chemical surface properties of bacterial strain and implant materials on in vitro bacterial adherence. Two bacterial strains (one hydrophilic strain and one hydrophobic strain) were used and the following were evaluated: bacterial cell adherence, SFE values as well as the Lifshitz-van-der Waals, the Lewis acid base components of SFE, the interfacial free energy and the non-dispersive interactions according to two complementary contact angle measurement methods: the sessile drop method and the captive bubble method. Our results showed similar patterns of adherent bacterial cells on saliva-coated cp-Ti and saliva-coated Ti-6Al-4V. These findings could suggest that bacterial colonization (i.e. plaque formation) is similar on saliva-coated cp-Ti and Ti-6Al-4V surfaces and indicate that both materials could be suitable for use as transgingival abutment or healing implant components. The same physico-chemical properties exhibited by saliva-coated cp-Ti and TA6V, as shown by the sessile drop method and the captive bubble method, could explain this similar bacterial colonisation. Therefore, higher values of total surface free energy of saliva-coated cp-Ti and saliva-coated TA6V samples (gamma(SV) approximately 65mJ/m(2)) were reported using the captive bubble method indicating a less hydrophobic character of these surfaces than with the sessile drop method (gamma(S) approximately 44.50mJ/m(2)) and consequently possible differences in oral bacterial retention according the theory described by Absolom et al. The number of adherent hydrophobic S. sanguinis cells was two-fold higher than that of hydrophilic S. constellatus cells. Our results confirm that physico-chemical surface properties of oral bacterial strains play a role in bacterial retention to implant materials in the presence of adsorbed salivary proteins.

Hand hygiene practices in a dental teaching center: Measures and improve.

OBJECTIVE: To measure the compliance and the quality of HH practices and the knowledge of the healthcare workers' of the university dental care center. MATERIALS AND METHODS: All educators and students present were eligible for inclusion in the study. Each healthcare professional was observed in care situation over a period of 30 min. The knowledge, attitudes and opinions were collected through a questionnaire. RESULTS: Number of healthcare professionals included was 190 (64.4%). Study group consisted of 151 students (74.4%) and 39 educators (42.4%). Out of a total number of expected disinfection of hands (993), 396 were made (39.9%). Educators had a higher compliance rates than students (63.7-35.8%, P = 10(-9)). Large differences were found between care situations (compliance higher before the first care to a patient and lower during installation of patient in dental X-ray area or at exit of dental X-ray area). Concerning hand rubbing (HR), 36.6% were performed correctly, and the main error was all steps of HR not observed (54.4%), and shorter duration (46.7%). The observance and the quality of HR were associated with better knowledge. CONCLUSION: This data suggests areas of improvement: (1) A comprehensive intervention including care organization/clinic ergonomics/planning/anticipation of materials needed for care; (2) the development of HH education program should include the educators, since the behavior of students is strongly influenced and formed by their mentor's attitude and behaviors.