ABSTRACT
Caries lesions develop when acid production from bacterial metabolism of dietary carbohydrates outweighs the various mechanisms that promote pH homeostasis, including bacterial alkali production. Therapies that provide arginine as a substrate for alkali production in supragingival oral biofilms have strong anticaries potential. The objective of this study was to investigate the metabolic profile of site-specific supragingival plaque in response to the use of arginine (Arg: 1.5% arginine, fluoride-free) or fluoride (F: 1,100 ppm F/NaF) toothpastes. Eighty-three adults of different caries status were recruited and assigned to treatment with Arg or F for 12 wk. Caries lesions were diagnosed using International Caries Detection and Assessment System II, and plaque samples were collected from caries-free and carious tooth surfaces. Taxonomic profiles were obtained by HOMINGS (Human Oral Microbe Identification using Next Generation Sequencing), and plaque metabolism was assessed by the levels of arginine catabolism via the arginine deiminase pathway (ADS), acidogenicity, and global metabolomics. Principal component analysis (PCA), partial least squares-discriminant analysis, analysis of variance, and random forest tests were used to distinguish metabolic profiles. Of the 509 active lesions diagnosed at baseline, 70 (14%) were inactive after 12 wk. Generalized linear model showed that enamel lesions were significantly more likely to become inactive compared to dentin lesions (P < 0.0001), but no difference was found when treatment with Arg was compared to F (P = 0.46). Arg significantly increased plaque ADS activity (P = 0.031) and plaque pH values after incubation with glucose (P = 0.001). F reduced plaque lactate production from endogenous sources (P = 0.02). PCA revealed differences between the metabolic profiles of plaque treated with Arg or F. Arg significantly affected the concentrations of 16 metabolites, including phenethylamine, agmatine, and glucosamine-6-phosphate (P < 0.05), while F affected the concentrations of 9 metabolites, including phenethylamine, N-methyl-glutamate, and agmatine (P < 0.05). The anticaries mechanisms of action of arginine and fluoride are distinct. Arginine metabolism promotes biofilm pH homeostasis, whereas fluoride is thought to enhance resistance of tooth minerals to low pH and reduce acid production by supragingival oral biofilms.
Subject(s)
Arginine/chemistry , Dental Plaque/metabolism , Fluorides/chemistry , Metabolome , Adult , Dental Caries/metabolism , Dental Caries/microbiology , Dental Plaque/microbiology , Double-Blind Method , Humans , Hydrogen-Ion Concentration , Lactic Acid/metabolism , Toothpastes/chemistryABSTRACT
O objetivo deste estudo foi avaliar o efeito de duas técnicas de inserção do compósito sobre o nível de infiltração marginal na interface dente/compósito restaurador. Foram preparadas 40 cavidades circulares medindo 4 mm de diamêtro por 3 mm de profundidade em dentes bovinos, que foram divididos em 4 grupos (n=10): Grupo 1 - Único encremento + P60; Grupo 2 - Único encremento + Definite; Grupo 3 - Três incrementos + P60 ; e Grupo 4 - Três incrementos + Definite. Todas as amostras foram armazenadas em água destilada a 37°C, por 24 horas e submetidas a 500 ciclos térmicos (5° e 55°) por 30 segundos em cada banho. Em seguida, os dentes foram imersos em solução de azul de metileno a 2 por cento, por 4 horas, e a microinfiltração avaliada. Os resultados submetidos ao teste estatístico de Kruskal-Wallis mostraram que a técnica de inserção em 3 incrementos para o Definite com 1 incremento; o P60 com 3 incrementos apresentou níveis de infiltração marginal estatisticamente menores em relação ao P60 e Definite, ambos com 1 incremento
