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Enamel remineralization by fluoride-releasing materials: proposal of a pH-cycling model
Rodrigues, Eliana;Delbem, Alberto Carlos Botazzo;Pedrini, Denise;Cavassan, Luciana;
Brazilian Dental Journal , 2010, DOI: 10.1590/S0103-64402010000500012
Abstract: this study proposes a ph-cycling model for verifying the dose-response relationship in fluoride-releasing materials on remineralization in vitro. sixty bovine enamel blocks were selected for the surface microhardness test (smh1). artificial caries lesions were induced and surface microhardness test (smh2) was performed. forty-eight specimens were prepared with z 100, fluroshield, vitremer and vitremer ? diluted - powder/liquid, and subjected to a ph-cycling model to promote remineralization. after ph-cycling, final surface microhardness (smh3) was assessed to calculate percent recovery of surface microhardness (%smhr). fluoride present in enamel (μg f/mm3) and in the ph-cycling solutions (μg f) was measured. cross-sectional microhardness was used to calculate mineral content (?z). there was no significant difference between z 100 and control groups on analysis performed on - %smhr, ?z, μg f and mg f/mm3 (p>0.05). results showed a positive correlation between %smhr and μg f/mm3 (r=0.9770; p=0.004), %smhr and μg f (r=0.9939; p=0.0000001), ? and μg f/mm3 (r=0.9853; p=0.0002), ? and μg f (r=0.9975; p=0.0000001) and between μg f/mm3 and μg f (r=0.9819; p=0.001). the ph-cycling model proposed was able to verify in vitro dose-response relationship of fluoride-releasing materials on remineralization.
Análise comparativa de desempenho de memórias associativas em redes neurais celulares
Corrêa, Leonardo Garcia;Delbem, Alexandre C B;Zhao, Liang;
Sba: Controle & Automa??o Sociedade Brasileira de Automatica , 2008, DOI: 10.1590/S0103-17592008000400008
Abstract: this paper presents a performance comparison of various methods for associative memory design in cellular neural networks (cnns). even though there have been an increasing interest in such kind of application for cnns, there is no comprehensive comparison of the performance among the proposed methods in the literature. in this paper, existing design methods are reviewed and their corresponding performances are measured in numerical simulations. the t -student test is then employed in order to compare the results obtained.
Ant-Based Phylogenetic Reconstruction (ABPR): A new distance algorithm for phylogenetic estimation based on ant colony optimization
Vittori, Karla;Delbem, Alexandre C.B.;Pereira, Sérgio L.;
Genetics and Molecular Biology , 2008, DOI: 10.1590/S1415-47572008000500027
Abstract: we propose a new distance algorithm for phylogenetic estimation based on ant colony optimization (aco), named ant-based phylogenetic reconstruction (abpr). abpr joins two taxa iteratively based on evolutionary distance among sequences, while also accounting for the quality of the phylogenetic tree built according to the total length of the tree. similar to optimization algorithms for phylogenetic estimation, the algorithm allows exploration of a larger set of nearly optimal solutions. we applied the algorithm to four empirical data sets of mitochondrial dna ranging from 12 to 186 sequences, and from 898 to 16,608 base pairs, and covering taxonomic levels from populations to orders. we show that abpr performs better than the commonly used neighbor-joining algorithm, except when sequences are too closely related (e.g., population-level sequences). the phylogenetic relationships recovered at and above species level by abpr agree with conventional views. however, like other algorithms of phylogenetic estimation, the proposed algorithm failed to recover expected relationships when distances are too similar or when rates of evolution are very variable, leading to the problem of long-branch attraction. abpr, as well as other aco-based algorithms, is emerging as a fast and accurate alternative method of phylogenetic estimation for large data sets.
In vitro comparison of the cariostatic effect between topical application of fluoride gels and fluoride toothpaste
Delbem, Alberto Carlos Botazzo;Brighenti, Fernanda Louren??o;Vieira, Ana Elisa de Mello;Cury, Jaime Aparecido;
Journal of Applied Oral Science , 2004, DOI: 10.1590/S1678-77572004000200008
Abstract: the aim of this study was to compare the effect of topical fluoride products [acidulated phosphate fluoride (apf) or neutral gel (nf) x fluoride toothpaste (mfp)], in respect to fluoride uptake and anticariogenic action. one hundred and twenty five blocks of human teeth, sorted in 5 groups according to the treatment, were submitted to ph cycling for ten days. the parameters analyzed were: fluoride uptake before and after ph cycling and surface (smh) and cross-sectional (csmh) microhardness of the enamel blocks. the results of fluoride concentration in enamel after the ph cycling showed an enhancement of fluoride uptake for all groups compared to sound control. no significant differences between apf and mfp were observed for surface microhardness, percentage change of surface microhardness and mineral loss. the volume percent mineral obtained from cross-sectional microhardness demonstrated that apf has a different lesion progression rate regarding subsurface carious lesion. the results suggest that professionally applied fluoride gel or frequent fluoride application in low concentration is a positive preventive measure for the control of dental caries.
Anticariogenic potencial of acidulate solutions with low fluoride concentration
Delbem, Alberto Carlos Botazzo;Tiano, Gilberto Carlos;Alves, Karina Mirela Ribeiro Pinto;Cunha, Robson Frederico;
Journal of Applied Oral Science , 2006, DOI: 10.1590/S1678-77572006000400004
Abstract: objetives: the aim of this study was to verify the anticariogenic effect of acidulate solutions with low naf concentration, using ph-cycling model and bovine enamel. material and methods: enamel blocks were submitted to the surface microhardness (smh) test and randomly divided in 12 experimental and one placebo groups. the blocks were submitted to ph cycling for 7 days, with daily applications once/day of 0.05% naf and 0.1% naf and twice/day of 0.02% naf solutions. four different ph: 4.0, 5.0, 6.0 and 7.0 were used. next, smh test was again used to determine the surface microhardness percentage change (%smh). data obtained for %smh were homogeneous and passed through variance analyses and tukey's test (5%) as far as fluoride concentrations and ph. results:the results showed that ph influenced %smh in 0.02% naf and 0.05% naf solutions with ph 4.0, which had less mineral loss compared to ph 7.0 (p<0.05). the 0.02% naf - ph 4.0, and 0.05% naf - ph 7.0 groups showed similar results (p>0.05). a dose-response relationship was observed among the tested solutions, with better anticariogenic effect for the 0.1% naf solution. conclusion: the results suggest that the addition of citric acid to acidulate mouth rinses reduce mineral loss.
Effect of fluoridated varnish and silver diamine fluoride solution on enamel demineralization: pH-cycling study
Delbem, Alberto Carlos Botazzo;Bergamaschi, Maurício;Sassaki, Kikue Takebayashi;Cunha, Robson Frederico;
Journal of Applied Oral Science , 2006, DOI: 10.1590/S1678-77572006000200005
Abstract: objective: in the present investigation, the anticariogenic effect of fluoride released by two products commonly applied in infants was evaluated. methods: bovine sound enamel blocks were randomly allocated to each one of the treatment groups: control (c), varnish (v) and diamine silver fluoride solution (d). the blocks were submitted to ph cycles in an oven at 37oc. next, surface and cross-sectional microhardness were assessed to calculate the percentage loss of surface microhardness (%sml) and the mineral loss (dz). the fluoride present in enamel was also determined. results: f/px10-3 (anova, p<0.05) in the 1st layer of enamel before ph-cycling were (c, v and d): 1.61a; 21.59b and 3.98c. the %smh (kruskal-wallis, p<0.05) were: -64.0a, -45.2b and -53.1c. %dz values (anova, p<0.05) were: -18.7a, -7.7b and -17.3a. conclusion: the data suggested that the fluoride released by varnish showed greater interaction with sound enamel and provided less mineral loss when compared with silver diamine solution.
Regional odontodysplasia: case report
Magalh?es, Ana Carolina;Pessan, Juliano Pelim;Cunha, Robson Frederico;Delbem, Alberto Carlos Botazzo;
Journal of Applied Oral Science , 2007, DOI: 10.1590/S1678-77572007000600002
Abstract: regional odontodysplasia (ro) is a rare developmental anomaly involving both mesodermal and ectodermal dental components in a group of contiguous teeth. it affects the primary and permanent dentitions in the maxilla and mandible or both jaws. generally it is localized in only one arch. the etiology of this dental anomaly is uncertain. clinically, affected teeth have an abnormal morphology, are soft on probing and typically discolored, yellow or yellowish-brown. radiographically, the affected teeth show a "ghostlike" appearance. this paper reports the case of a 5-year-old girl presenting this rare anomaly on the left side of the maxillary arch, which crossed the midline. the primary maxillary left teeth (except for the canine) and the primary maxillary right central incisor were missing due to previous extractions. the permanent teeth had a "ghostlike" appearance radiographically. the treatment performed was rehabilitation with temporary partial acrylic denture and periodic controls. in the future, the extraction of affected permanent teeth and rehabilitation with dental implants will be evaluated. the presentation of this case adds valuable information to pediatric dentists to review special clinical and radiographic features of ro, which will facilitate the diagnosis and treatment of patients with this condition.
Microhardness and fluoride release of restorative materials in different storage media
Silva, Kélio Garcia;Pedrini, Denise;Delbem, Alberto Carlos Botazzo;Cannon, Mark;
Brazilian Dental Journal , 2007, DOI: 10.1590/S0103-64402007000400007
Abstract: this study evaluated the surface microhardness and fluoride release of 5 restorative materials - ketac-fil plus, vitremer, fuji ii lc, freedom and fluorofil - in two storage media: distilled/deionized water and a ph-cycling (ph 4.6). twelve specimens of each material, were fabricated and the initial surface microhardness (ism) was determined in a shimadzu hmv-2000 microhardness tester (static load knoop). the specimens were submitted to 6- or 18-h cycles in the tested media. the solutions were refreshed at the end of each cycle. all solutions were stored for further analysis. after 15-day storage, the final surface microhardness (fsm) and fluoride release were measured. fluoride dose was measured with a fluoride-specific electrode (orion 9609-bn) and digital ion analyzer (orion 720 a). the variables ism, fsm and fluoride release were analyzed statistically by analysis of variance and tukey's test (p<0.05). there was significant difference in fsm between the storage media for vitremer (ph 4.6 = 40.2 ± 1.5; water = 42.6 ± 1.4), ketac-fil plus (ph 4.6 = 73.4 ± 2.7; water = 58.2 ± 1.3) and fluorofil (ph 4.6 = 44.3 ± 1.8; water = 38.4 ± 1.0). ketac-fil plus (9.9 ± 18.0) and fluorofil (4.4 ± 1.3) presented higher fluoride release in water, whereas vitremer (7.4 ± 7.1), fuji ii lc (5.7 ± 4.7) and freedom (2.1 ± 1.7) had higher fluoride release at ph 4.6. microhardness and fluoride release of the tested restorative materials varied according to the storage medium.
Fluoride release by restorative materials before and after a topical application of fluoride gel
Pedrini, Denise;Delbem, Alberto Carlos Botazzo;Fran?a, Juliana Gomes Macedo de;Machado, Thiago de Medeiros;
Pesquisa Odontológica Brasileira , 2003, DOI: 10.1590/S1517-74912003000200007
Abstract: the release of fluoride from restorative materials (vitremer, ketac-fil, fuji ii lc and freedom) was evaluated during two 15-day periods, before and after a topical application of acidulated phosphate fluoride gel (apf). for each material, 6 specimens were made, which were immersed in 2 ml of deionized water. the fluoride concentration dosages in the solutions were read at intervals of 24 hours for 15 days. after this period, the specimens of each material received treatment with apf gel for 4 minutes and the fluoride released was analyzed at 24-hour intervals during the following 15 days. the analysis of variance and the tukey test (p < 0.05) showed that the total mean fluoride released during the initial 15 days was greater for vitremer and ketac-fil and lower for fuji ii lc and freedom; and in the final 15 days there was a difference in release readings, with the greatest value for vitremer, followed by fuji ii lc, ketac-fil and freedom. the comparison of the results between the 1st day and the 16th day (after gel application) showed a greater fluoride release on the 16th day for vitremer, fuji ii lc and freedom and was equal for ketac-fil. although all the materials evaluated gained fluoride with the application of apf, the data suggest that the resin-modified ionomers are more efficient in releasing fluoride to the medium than the other materials.
Modification of a Brazilian smectite clay with different quaternary ammonium salts
Delbem, Maria Flávia;Valera, Ticiane S.;Valenzuela-Diaz, Francisco R.;Demarquette, Nicole R.;
Química Nova , 2010, DOI: 10.1590/S0100-40422010000200015
Abstract: in this work, a smectite clay from the state of paraiba, brazil, was treated with six different types of ammonium salts, which is an usual method to enhance the affinity between the clay and polymer for the preparation of nanocomposites. the clays, before and after modification, were characterized by x ray diffraction. the conformation of the salts within the platelets of the clay depended on the number of long alkyl chains of the salt. the thermal stability of the clays was also studied. the ammonium salts thermal decomposition was explained in light of their position within the organoclays.
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