FMD - Artigos em Revistas Internacionais
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- Examination of dietary methylmercury exposure in the Casa Pia study of the health effects of dental amalgams in childrenPublication . Evens, Carina C.; Martin, Michael D.; Woods, James S.; Luís, Henrique Soares; Bernardo, Mário; Leitão, Jorge; Simmonds, P. Lynne; Liang, Lian; DeRouen, TimothyThis study examined methylmercury concentrations in blood of children participating in the Casa Pia Study of the Health Effects of Dental Amalgams in Children over a 1-yr period and related them to their diets in terms of fish and other seafood consumption. One hundred and fifty children between the ages of 8 and 10 yr who were residents of the Casa Pia School System of Lisbon, Portugal, participated. Parents or caregivers completed a food frequency questionnaire designed specifically for this study at baseline. Children provided urinary and blood samples for mercury determinations at baseline and at 1 yr following placement of dental tooth fillings. Mercury levels in fish samples from children’s diets were also obtained. Mercury determinations in urine, blood, and fish were performed using cold vapor atomic fluorescence spectroscopy. The mean value of baseline methylmercury concentrations in blood increased as the report of seafood consumption increased, although not statistically significantly. However, blood methylmercury and total mercury concentrations were significantly lower at 1-yr follow-up than at baseline. Sixty-one percent of parents/ caregivers reported that their children consumed fish on a weekly basis. The fish offered at a sample of the schools contained low levels of methylmercury ( range 13.9–23.6 ng/ g) . Thus, children participating in the Casa Pia dental amalgam study are exposed to low dietary levels of methylmercury by way of fish consumption, and this finding was reflected in the low mean blood methylmercury concentrations observed. The present findings indicate that dietary methylmercury is not a significant source of mercury exposure and is not likely to confound the association of dental amalgam mercury with potential health effects in the present study.
- Persistence of oral candida albicans carriage in healthy portuguese schoolchildren followed for 3yearsPublication . Starr, J. R.; White, T. C.; Leroux, B. G.; Luís, H. S.; Bernardo, M.; Leitão, J.; Roberts, M. C.Little is known about carriage of Candida albicans, the predominant pathogenic yeast in oral infection, in children. We cultured buccal mucosal and gingival swabs from 150 Portuguese children to investigate the prevalence of C. albicans at baseline (before dental treatment), post-treatment, and 12, 24, and 36months post-baseline. The children, aged 8 to 11years at baseline, had no systemic disease or clinical symptoms of oral candidiasis. At each successive visit, respectively, 47, 32, 21, 27, and 28% of children were C. albicans positive, resulting in an almost 50% reduction in prevalence from baseline to post-treatment (P_0.0005). Children who carried C. albicans at one visit had 3 to 20 times greater odds of carrying C. albicans at another visit. C. albicans was cultured from 12 children at all time-points and from 10 children at four time-points. Children with oral C. albicans frequently maintained carriage over time, even with regular dental care.
- Presence and antibiotic resistance of porphyromonas gingivalis, prevotella intermedia, and prevotella nigrescens in childrenPublication . Sanai, Y.; Persson, GR; Starr, JR.; Luís, HS; Bernardo, M.; Leitão, J.; Roberts, MCBackground/aims: Only limited information exists about the prevalence in children of pathogens associated with periodontitis. The aim of the present study was to determine by culture whether 8–11-year-old children carry Porphyromonas gingivalis, Prevotella intermedia, and/or P. nigrescens in samples from the gingiva and/or the buccal mucosa taken before, and after caries treatment and oral hygiene instruction. A second aim was to assess the proportion of subjects who had gram-negative anaerobes carrying the tet(Q) and erm(F) genes, suggesting antibiotic resistance to tetracycline or erythromycin. Method: A total of 150 children provided gingival and buccal swab bacterial samples that were cultured for P. gingivalis, P. intermedia, and P. nigrescens. The species was verified using DNA–DNA hybridization with species-specific probes made from the variable region of the 16S rRNA sequences. Antibiotic-resistant genes, tet(Q) and erm(F), were identified using specific DNA–DNA hybridization with specific DNA probes. Results: A total of 116 isolates of black-pigmented bacteria were cultured from 47 (31%) of 150 children. Five isolates were identified as P. gingivalis, 29 as P. intermedia, 33 as P. nigrescens, and 49 as other species. In general, the bacteria were not culturable at more than one time period. We found that 55% of these 47 children harbored black pigmented bacteria that carried either one or both of the two antibiotic-resistant genes studied (tet(Q), and erm(F)). Conclusion: The present study demonstrated that children not exposed to regular dental treatment carry bacteria outside the gingival sulcus that have been associated with periodontitis, and that standard treatment procedures may not clear;the presence of the putative pathogens. In addition, antibiotic-resistant genes are common in identifiable gram-negative anaerobes, including putative pathogens.
- Distribution of mef(A) in Gram-Positive Bacteria from Healthy Portuguese ChildrenPublication . Luna, Vicki A.; Heiken, Marc; Judge, Kathleen; Ulep, Catherine; Van Kirk, Nicole; Luis, Henrique; Bernardo, Mário; Leitão, José; Roberts, Marilyn C.We screened 615 gram-positive isolates from 150 healthy children for the presence of the erm(A), erm(B), erm(C), erm(F), and mef(A) genes. The mef(A) genes were found in 20 (9%) of the macrolide-resistant isolates, including Enterococcus spp., Staphylococcus spp., and Streptococcus spp. Sixteen of the 19 gram-positive isolates tested carried the other seven open reading frames (ORFs) described in Tn1207.1, a genetic element carrying mef(A) recently described in Streptococcus pneumoniae. The three Staphylococcus spp. did not carry orf1 to orf3. A gram-negative Acinetobacter junii isolate also carried the other seven ORFs described in Tn1207.1. A Staphylococcus aureus isolate, a Streptococcus intermedius isolate, a Streptococcus sp. isolate, and an Enterococcus sp. isolate had their mef(A) genes completely sequenced and showed 100% identity at the DNA and amino acid levels with the mef(A) gene from S. pneumoniae.
- The dental hygiene program in PortugalPublication . Luís, H. S.; Ribeiro, S.; Albuquerque, T.The dental hygiene program is a fairly recent addition in the field of the health professions in Portugal. In the past 19 years, the programme has developed community activities alongside with clinical work. This programme provides an education that is responsive, scientific and professional, in a learning environment that is dynamic, student-centred and that encourages collaboration between students and faculty. The community activities play a major role in the curricula of the programme and allow the students to develop skills in working with a wide range of population groups and to attend to their specific needs. Dental hygienists are integrated in health teams and work under the supervision of a physician or a dentist. Among other responsibilities, the following functions are part of the scope of the profession: to participate in health education programmes and sensitise the population to the prevention of dental diseases, to participate in the planning, implementation, and evaluation of the public health programmes and to perform clinical treatment for prevention and control of gingivitis, periodontitis, and dental caries. An overview of the activities developed in the year 2002 and future perspectives are presented in this article.
- Gram-positive merA gene in gram-negative oral and urine bacteriaPublication . Ojo, Kayode K.; Tung, Diane; Luis, Henrique; Bernardo, Mario; Leitão, Jorge; Roberts, Marilyn C.Clinical mercury resistant (Hgr) Gram-negative bacteria carrying Gram-positive mercury reductase (merA)-like genes were characterized using DNA–DNA hybridization, PCR and sequencing. A PCR assay was developed which discriminated between the merA genes related to Staphylococcus and those related to the Bacillus/Streptococcus merA genes by the difference in size of the PCR product. DNA sequence analysis correlated with the PCR assay. The merA genes from Acinetobacter junii, Enterobacter cloacae and Escherichia coli were sequenced and shared 98–99% identical nucleotide (nt) and 99.6–100% amino acid identity with the Staphylococcus aureus MerA protein. A fourth merA gene, from Pantoeae agglomerans, was partially sequenced (60%) and had 99% identical nt and 100% amino acid identity with the Streptococcus oralis MerA protein. All the Hgr Gram-negative bacteria transferred their Gram-positive merA genes to a Gram-positive Enterococcus faecalis recipient with the resulting transconjugants expressing mercury resistance. These Gram-positive merA genes join Gram-positive tetracycline resistance and Gram-positive macrolide resistance genes in their association with mobile elements which are able to transfer and express in Gram-negative bacteria.
- The mef(A) gene predominates among seven macrolide resistance genes identified in gram-negative strains representing 13 genera, isolated from healthy portuguese childrenPublication . Ojo, K. K.; Ulep, C.; Van Kirk, N.; Luís, H.; Bernardo, M.; Leitão, J.; Roberts, M. C.Of the 176 randomly selected, commensal, gram-negative bacteria isolated from healthy children with low exposure to antibiotics, 138 (78%) carried one or more of the seven macrolide resistance genes tested in this study. These isolates included 79 (91%) isolates from the oral cavity and 59 (66%) isolates from urine samples. The mef(A) gene, coding for an efflux protein, was found in 73 isolates (41%) and was the most frequently carried gene. The mef(A) gene could be transferred from the donors into a gram-positive E. faecalis recipient and a gram-negative Escherichia coli recipient. The erm(B) gene transferred and was maintained in the E. coli transconjugants but was found in 0 to 100% of the E. faecalis transconjugants tested, while the other five genes could be transferred only into the E. coli recipient. The individual macrolide resistance genes were identified in 3 to 12 new genera. Eight (10%) of the oral isolates and 30 (34%) of the urine isolates for which the MICs were 2 to >500 _g of erythromycin per ml did not hybridize with any of the seven genes and may carry novel macrolide resistance genes.
- Color matching with conservative porcelain laminate veneers: a case reportPublication . Lampreia, Marina; Oliveira, Sofia; Leitão, JorgeIn aesthetic dentistry, porcelain laminate veneers (PLVs) have demonstrated excellent clinical behavior in terms of periodontal reaction and durability. Of the ceramic systems presently available for the fabrication of PLVs, among the most commonly used are feldspathic porcelain applied via the traditional powder-slurry method, heat-pressed leucite-reinforced ceramics, and CAD/CAMprocessed ceramics. The success of the PLV is greatly determined by the nature of the bond established between the tooth surface and the PLV. For this purpose, silicon oxide etchable ceramics are generally the most reliable. As their glassy phase is selectively dissolved by the acid and the crystals become exposed, an excellent retentive surface is created. Silicon oxide ceramics can be processed according to the pressed technique. This method enhances strength, homogeneity, and fit. All-ceramic systems (eg, OPC, Pentron Laboratory Technologies, Wallingford, CT; Authentic, Microstar Corporation, Lawrenceville, GA; IPS Empress, Ivoclar Vivadent, Amherst, NY), are examples of pressed ceramics obtained from evenly dispersed leucite crystals. This article presents the treatment of severely compromised aesthetics in the anterior region using a combination of tooth whitening and contemporary composite and porcelain restorative materials.
- Sealing of human dentinal tubules by KrF 248 nm laser radiationPublication . Sivakumar, M.; Oliveira, V.; Vilar, R.; Oliveira, S.; Leitão, J.Exposure of dentinal tubules is a common cause of dental hypersensitivity to thermal, mechanical, or chemical stimuli. Treatment for this syndrome should be fast, painless on application, and long lasting, but most treatments presently available are ineffective or relatively short lived. The aim of the present investigation was to evaluate the potential of excimer laser treatment as a method to seal tubules, thus reducing sensitivity. The laser treatment was performed on samples with a wide range of orientations of the tubules in relation to the samples surfaces extracted from caries-free human teeth by cross-sectional cutting and on noncarious lesions. The samples were processed using 248 nm wavelength pulsed laser radiation with a pulse duration of 30 ns and fluences in the range 0.5–2 J /cm2. Irrespective of their orientation in relation to the laser beam, tubules may be sealed by laser processing if adequate parameters are used. Tubule sealing is either due to the formation of cone-like features around individual tubules or because the entire surface is covered by a thin layer of resolidified material. The results achieved both on flat samples and in noncarious lesions are reproducible, suggesting that this method is potentially useful for dental hypersensitivity treatment.
- Staphylococcus efflux msr(A) gene characterized in streptococcus, enterococcus, corynebacterium, and pseudomonas isolatesPublication . Ojo, Kayode K.; Striplin, Megan J.; Ulep, Catherine C.; Close, Natasha S.; Zittle, Jennifer; Luís, Henrique; Bernardo, Mario; Leitão, Jorge; Roberts, Marilyn C.The staphylococcal msr(A) gene, coding for a macrolide efflux protein, was identified in three new grampositive genera and one gram-negative genus. These msr(A) genes shared 99 to 100% identity with each other and the staphylococcal gene. This study demonstrates that the msr(A) gene has a wider host range than previously reported.