Effect of iontophoresis on fluoride uptake in enamel with artificial caries lesion

Abstract: Iontophoresis is a noninvasive technique, based on the application of a constant low-intensity electric current to facilitate the release of a variety of drugs, whether ionized or not, through biological membranes. The objective of this research was to evaluate the effect of iontophoresis using different electric current intensities on the uptake of fluoride in dental enamel with artificial caries lesions. In this in vitro operator-blind experiment, bovine enamel blocks (n = 10/group) with caries-like lesions and predetermined surface hardness were randomized into 6 groups: placebo gel without fluoride applied with a current of 0.8 mA (negative control), 2% NaF gel without application of any current, and 2% NaF gel applied with currents of 0.1, 0.2, 0.4 and 0.8 mA. Cathodic iontophoresis was applied for 4 min. The concentration of loosely bound fluoride (calcium fluoride) and firmly bound fluoride (fluorapatite) was determined. The results were analyzed by the nonparametric Kruskal-Wallis and Dunn tests. Iontophoresis at 0.8 mA, combined with the application of fluoridated gel (2% NaF), increased fluoride uptake in enamel with caries-like lesions, as either calcium fluoride or fluorapatite.

Anticaries potential of a fluoride mouthrinse evaluated in vitro by validated protocols

This blind and randomized study tested in vitro, using validated protocols, the anticaries potential of an experimental fluoride mouthrinse. One-hundred enamel slabs, half sound and half with caries-like lesions (carious), all with known surface microhardness (SMH), were submitted to 3 treatment groups: A) a placebo mouthrinse (negative control); B) a positive control mouthrinse containing 0.05 percent NaF; and C) an experimental formulation containing 0.05 percent NaF and cetylpyridinium chloride as an antibacterial substance. To evaluate the formation of F products on enamel, sound (n=10) and carious (n=10) slabs were treated with the formulations during 10 min and loosely and firmly-bound F formed in enamel were determined after extraction with alkali and acid, respectively. To evaluate the inhibition of enamel demineralization, sound enamel slabs (n=10) were treated with the mouthrinse formulations 2x/day during 1 min and subjected to a pH-cycling regimen simulating a cariogenic challenge (demineralization). To evaluate enamel remineralization, the carious slabs (n=10) were submitted to the treatments 3x/day and subjected to a pH-cycling model simulating a remineralizing condition. After 8 days, enamel SMH was determined again and the percentage of SMH loss or SMH recovery was calculated for the sound and carious slabs, respectively. The experimental formulation was superior to the negative control (p<0.05) and equivalent to the positive control (p>0.05) in the formation of F products in enamel, and in the inhibition of enamel demineralization and enhancement of remineralization. These data suggest that the tested experimental fluoride mouthrinse has anticaries potential.

Este estudo in vitro, cego e randomizado avaliou o potencial anticárie de uma formulação experimental de enxaguatório fluoretado (F), usando protocolos previamente validados. Blocos de esmalte (120), 60 hígidos e 60 com lesão artificial de cárie, com microdureza de superfície (MDS) conhecida, foram submetidos a 3 grupos de tratamentos: A) Enxaguatório placebo (controle negativo); B) Controle positivo contendo NaF 0,05 por cento e C) Uma formulação experimental contendo NaF 0,05 por cento e cloreto de cloreto de cetil-piridínio como antibacteriano. Para testar a capacidade de formação de produtos fluoretados no esmalte, blocos hígidos (n=10) e cariados (n=10) foram tratados durante 10 min e os fluoretos fracamente e fortemente ligados formados foram determinados após extração com álcali e ácido, respectivamente. Para avaliar a inibição da desmineralização do esmalte, os blocos hígidos (n=10) foram tratados com as formulações 2 x/dia durante 1 min e submetidos a um modelo de ciclagem de pH, simulando o processo de desmineralização. Para avaliar a ativação da remineralização do esmalte, os blocos com lesões de cárie (n=10) foram tratados 3 x/dia e submetidos a um modelo de ciclagens de pH, simulando uma condição de remineralização. Após 8 dias, a MDS do esmalte foi novamente determinada e as porcentagens de sua redução ou aumento foram calculadas, respectivamente para os blocos hígidos ou com lesão de cárie. A formulação experimental foi superior ao controle negativo (p<0,05) e equivalente ao positivo (p>0,05), na formação de produtos fluoretados no esmalte e na inibição de sua desmineralização e ativação da remineralização. Conclui-se que o enxaguatório experimental apresenta fluoreto ativo com potencial para controlar cárie dental.

Formaçäo in vitro de fluoreto de cálcio e fluorapatita em esmalte humano após a aplicaçäo de gel flúor-fosfato acidulado durante 1 e 4 minutos / In vitro calcium fluoride and fluorapatite formation in human dental enamel after apf gel aplication during 1 and 4 minutes

Os autores, através de uma metodologia in vitro, avaliam 2 tempos de aplicaçäo de gel flúor-fosfato acidulado (FFA), 1 e 4 min, em esmalte dental humano hígido. Realizaram análise de fluoreto de cálcio (flúor fracamente ligado ao esmalte) e fluoratita (flúor fortemente ligado ao esmalte). Encontraram, através do teste näo paramétrico de Kruskall-Wallis H, considerando nível de significância de 1 por cento, diferença significante entre o grupo controle e os grupos testes. Näo encontraram diferença significante entre os dois grupos testes