Celso Silva Queiroz

pH-cycling models to evaluate the effect of low fluoride dentifrice on enamel de- and remineralization

Since the currently available pH-cycling models do not differentiate the anti-caries potential of dentifrices with low fluoride (F) concentration, two models were developed and tested in the present. Bovine enamel blocks were subjected to the models and treated with F solutions containing from 70 to 280 microg F/mL in order to validate them in terms of dose-response effect. The models were also tested by evaluating the dentifrices Colgate Baby (500 microg F/g, as a low fluoride dentifrice), Tandy (1,100 microg F/g, as an active F-dentifrice) and Crest (1,100 microg F/g, as positive control). Enamel mineral loss or gain was assessed by surface and cross-sectional microhardness, and lesion depth was analyzed by polarized light microscopy. The pH-cycling models showed F dose-response effect either reducing enamel demineralization or enhancing remineralization. The low F dentifrice presented anti-caries potential, but it was not equivalent to the dentifrices containing 1,100 microg F/g. These data suggest that the models developed in this study were able to evaluate the anti-caries potential of low F dentifrice either on resistance to demineralization or on enhancement of remineralization.

Caries Progression and Inhibition in Human and Bovine Root Dentine in situ

Since the use of bovine instead of human dentine to evaluate cariogenic and anticariogenic substances is not well established, this in situ study was conducted. Eleven volunteers wore palatal acrylic devices containing 4 dentine slabs (2 human and 2 bovine). Sucrose solution (20%) was dripped over all slabs 4 times a day, simulating a cariogenic challenge. Dentifrice slurries, fluoridated or not, were dripped over specified dentine slabs 3 times a day to evaluate caries reduction. After 14 days, the biofilm formed on the dentine slabs was collected for microbiological analysis. In dentine, mineral loss (ΔZ) and lesion depth (LD) were determined by cross-sectional microhardness and by polarized light microscopy, respectively. The total streptococci and mutans streptococci counts in the biofilm formed either on human or on bovine slabs, whether treated or not with fluoride dentifrice, were not statistically different. The ΔZ and the LD values of dentine treated with fluoride dentifrice were significantly lower than the values of dentine treated with non-fluoride dentifrice. The differences in the ΔZ and LD values between the human and bovine dentine were not statistically significant. The results suggest that bovine dentine can be used instead of human to evaluate caries development and inhibition.

Fluoride and aluminum in teas and tea-based beverages

OBJECTIVE To evaluate fluoride and aluminum concentration in herbal, black, ready-to-drink, and imported teas available in Brazil considering the risks fluoride and aluminum pose to oral and general health, respectively. METHODS One-hundred and seventy-seven samples of herbal and black tea, 11 types of imported tea and 21 samples of ready-to-drink tea were divided into four groups: I-herbal tea; II-Brazilian black tea (Camellia sinensis); III-imported tea (Camellia sinensis); IV-ready-to-drink tea-based beverages. Fluoride and aluminum were analyzed using ion-selective electrode and atomic absorption, respectively. RESULTS Fluoride and aluminum levels in herbal teas were very low, but high amounts were found in black and ready-to-drink teas. Aluminum found in all samples analyzed can be considered safe to general health. However, considering 0.07 mg F/kg/day as the upper limit of fluoride intake with regard to undesirable dental fluorosis, some teas exceed the daily intake limit for children. CONCLUSIONS Brazilian and imported teas made from Camellia sinensis as well as some tea-based beverages are sources of significant amounts of fluoride, and their intake may increase the risk of developing dental fluorosis.OBJETIVO: Avaliar as concentracoes de fluor e aluminio em chas brasileiros de ervas, preto e bebidas a base de cha, como em chas preto importados considerando seus riscos para, respectivamente, a saude oral e geral. METODOS: Foram analisadas 177 amostras de cha de ervas e cha preto, 11 tipos de cha preto importados e 21 amostras de bebidas a base de cha. Fluor e aluminio foram determinados apos infusao dos chas de ervas e pretos. As determinacoes de fluor e aluminio foram feitas por eletrodo especifico e absorcao atomica, respectivamente. RESULTADOS: A quantidade de fluor e aluminio encontrada nos chas de erva foi muito baixa, mas foi alta nos chas preto e nas bebidas a base de cha. A quantidade de aluminio em todas amostras analisadas pode ser considerada segura para a saude geral. Entretanto, considerando 0,07 mg F/kg/dia como o limite superior de risco de fluorose esteticamente comprometedora, alguns chas preto e algumas bebidas a base de cha podem por si so submeter criancas a uma dose diaria superior ao limite. CONCLUSOES: Chas preto brasileiros e importados, assim como bebidas a base de cha sao fontes de quantidades significantes de fluor e sua ingestao diaria pode aumentar o risco de fluorose dental

Assessment of Bone Healing in Rabbit Calvaria Grafted with Three Different Biomaterials

This study evaluated the bone regeneration process in rabbit calvaria induced by three types of biomaterials: two xenogenous, consisting of deproteinized bovine bone, while the other was alloplastic, based on biphasic calcium phosphate. Five New Zealand white rabbits weighing between 2,900 and 3,500 g were submitted to four standard 8 mm-diameter perforations at the parietal bone. Three perforations were filled with three grafts and biomaterials, two of them received bovine Bio-Oss® and Endobon® Xenograft Granules, and the other consisted of fully alloplastic Straumann® Bone Ceramic. The fourth remaining cavity was used as control with coagulum. After eight weeks, the animals were sacrificed, and the samples were prepared for morphometric and qualitative analysis. The cavities filled with alloplastic biomaterials showed higher percentages of newly formed bone (p<0.05), while the cavities with xenogenous biomaterials showed higher amount of residual graft (p<0.05). Although the results showed greater bone formation with Straumann® Bone Ceramic, further studies are required to prove which is the more effective biomaterial for bone induction process.

Influência da microabrasão do esmalte sobre o desenvolvimento de cárie artificial:estudo piloto in vitro

O objetivo deste estudo piloto foi avaliar a microdureza interna do esmalte dental microabrasionado, apos ter sido submetido a um modelo de ciclagem de pH. Material e metodos: 25 blocos de esmalte obtidos de dentes com fluorose (TF2 ou TF3) foram selecionados (5 por grupo) e submetidos a cinco tratamentos: Grupo l-Controle (sem tratamento); Grupo II - Opalustre; Grupo III - Opalustre+FN; Grupo IV - acido fosforico; Grupo V - acido fosforico+FN. Os blocos foram submetidos a um modelo de ciclagem de pH durante quatorze dias, alternando periodos de desmineralizacao (6h, 2mM de Ca e P04, 0,075M de tampao acetato, pH 4,3) e remineralizacao (17h, 1,5mM de Ca, 0,9mM de P04, 0,015 de KCI, 0,1 M de tampao TRIS, pH 7,0). A microdureza em seccao longitudinal foi determinada e o valor Z ( por cento perda mineral) foi calculado. Resultados: a media e desvio-padrao para os Grupos I, II, III, IV e V, foram respectivamente: 485,2 +/- 64,4 a; 345,3 +/- 44,5 b; 366,9 +/- 34,8 b; 364,4 +/- 42,6 b; 366,6 +/- 43,6 b (Teste de Tukey - p