Effect of dentifrices with different pH and fluoride concentrations on fluoride levels in biofilm and nails: an RCT.

PURPOSE: to evaluate the effect of dentifrice pH and fluoride concentration ([F]) on fluoride uptake on the biofilm and nails of children from a non-fluoridated area. METHODS: two hundred and twenty-eight two- to four-year-old children were randomly allocated into 3 groups according to the type of dentifrice: G1: 1100 µg F/g, pH 4.5 (n = 76); G2: 750 µg F/g, pH 4.5 (n = 74); and G3: 1100 µg F/g, pH 7.0 (n = 78). Nails were collected at 4, 8, and 12 months after starting dentifrice use and biofilm was collected 5 and 60 minutes after toothbrushing. The concentrations of F in nails and biofilm were analyzed by HMDS facilitated diffusion. Data were analyzed by Kruskal-Wallis/Mann-Whitney's test and the comparison between biofilm collection times was done using Wilcoxon test (p £ 0.05). RESULTS: a significant reduction of [F] in biofilm was observed 60 minutes after toothbrushing, regardless of the dentifrice used. However, 5 minutes after toothbrushing, G1 had a significantly higher [F] compared to G2 and G3, and 60 minutes after toothbrushing, [F] was significantly higher for G1 and G2 compared to G3. G1 and G3 had significantly higher [F] in the nails compared to G2. CONCLUSION: a lower dentifrice concentration is a relevant factor for the reduction of excessive fluoride intake. The use of a low-F acidified dentifrice combines the reduction of fluoride uptake with caries prevention by leading to greater incorporation of F into the biofilm over time.

Effect of dentifrices with different pH and fluoride concentrations on fluoride levels in biofilm and nails: an RCT

Abstract: Purpose: to evaluate the effect of dentifrice pH and fluoride concentration ([F]) on fluoride uptake on the biofilm and nails of children from a non-fluoridated area. Methods: two hundred and twenty-eight two- to four-year-old children were randomly allocated into 3 groups according to the type of dentifrice: G1: 1100 μg F/g, pH 4.5 (n = 76); G2: 750 μg F/g, pH 4.5 (n = 74); and G3: 1100 μg F/g, pH 7.0 (n = 78). Nails were collected at 4, 8, and 12 months after starting dentifrice use and biofilm was collected 5 and 60 minutes after toothbrushing. The concentrations of F in nails and biofilm were analyzed by HMDS facilitated diffusion. Data were analyzed by Kruskal-Wallis/Mann-Whitney's test and the comparison between biofilm collection times was done using Wilcoxon test (p £ 0.05). Results: a significant reduction of [F] in biofilm was observed 60 minutes after toothbrushing, regardless of the dentifrice used. However, 5 minutes after toothbrushing, G1 had a significantly higher [F] compared to G2 and G3, and 60 minutes after toothbrushing, [F] was significantly higher for G1 and G2 compared to G3. G1 and G3 had significantly higher [F] in the nails compared to G2. Conclusion: a lower dentifrice concentration is a relevant factor for the reduction of excessive fluoride intake. The use of a low-F acidified dentifrice combines the reduction of fluoride uptake with caries prevention by leading to greater incorporation of F into the biofilm over time.

Avaliação in vitro de propriedades mecânicas de resinas compostas com adição de zircônia e de resina composta com adição de zircônia e diatomita utilizadas em restaurações semidiretas / In vitro evaluation of mechanical properties of composite resins with the addition of zirconia and composite resin with the addition of zirconia and diatomite used in semi-direct restorations

INTRODUÇÃO: A incorporação de partículas de carga às resinas compostas tem o papel de melhorar suas propriedades físicas e mecânicas, conferindo uma maior resistência às restaurações. Muitos compósitos possuem nanopartículas incorporadas a sua composição, como quartzo, zircônia, sílica e, mais recentemente, a diatomita, que é uma rocha sedimentar rica em sílica. A adição dessas partículas busca aumentar a área de superfície e promover maior interação com a matriz orgânica. OBJETIVOS: Esse estudo objetivou avaliar resistência de união (RU), padrão de fratura (PF), profundidade de polimerização (PP), resistência a flexão (RF) e módulo de elasticidade (ME) de resinas compostas convencionais com adição de zircônia, com adição de zircônia e diatomita e de incremento único, em restaurações confeccionadas pela técnica semidireta, em dois tempos de envelhecimento (24h e 6 meses). METODOLOGIA: Foram criadas cavidades troncocônicas em dentina de incisivos bovinos (N=136), para confecção de restaurações semidiretas utilizando as resinas: Bulk Fill (BF) (3M ESPE®), Resina Z250 XT (Z250XT) (3M ESPE®), Resina Zirconfill (ZF) (BM4®) e Resina Z350 XT (Z350XT) (3M ESPE®), cimentadas com cimento resinoso dual autocondicionante RelyX Ultimate (3M ESPE®). As amostras foram armazenadas por 24 horas e 6 meses em estufa a 37ºC antes da realização dos testes de RU e PF, sendo as amostras com 24 horas selecionadas para o teste de PP. Para os testes de RF e ME, utilizando uma matriz de silicone, foram confeccionados palitos padronizados (10,0 mm. x 1,0 mm. de altura x 2,0 mm.) para cada resina testada (n=10) e também armazenados em estufa a 37ºC por 24h e 6 meses antes da realização dos testes. RESULTADOS: Na análise imediata, a resina ZF apresentou a maior RU entre os grupos e apresentou diferença estatisticamente significativa com o grupo BF. Já a resina Z350 aumentou sua RU com o tempo de envelhecimento. Não houve diferença entre a RF das resinas analisadas após 24h, porém após 6 meses a Z250 apresentou a menor média, enquanto os demais grupos aumentaram a RF com o tempo, sendo o maior aumento para o grupo da ZF. Com relação ao ME, apenas as resinas Z350 e ZF apresentaram diferença estatisticamente significativa com o tempo de envelhecimento das amostras, aumentando esse valor. As fraturas mistas foram predominantes para todos os compósitos em ambos os tempos de envelhecimento e para PP não foram encontradas diferenças estatisticamente significativas entre os grupos de estudo. CONCLUSAO: As resinas que continham adição de zircônia ou zircônia e diatomita no seu conteúdo inorgânico, bem como a resina de incremento único mostraram comportamentos positivos diante as propriedades de RU, a RF e o ME, principalmente para as resinas Z350XT e ZF. Estudos clínicos são recomendados para comprovar os resultados desse estudo laboratorial (AU).

INTRODUCTION: The incorporation of filler particles in composite resins has the role of improving their physical and mechanical properties, providing greater resistance to restorations. Many composites have nanoparticles incorporated into their composition, such as quartz, zirconia, silica and, more recently, diatomite, which is a silica-rich sedimentary rock. The addition of these particles seeks to increase the surface area and promote greater interaction with the organic matrix. OBJECTIVES: This study aimed to evaluate bond strength (RU), fracture pattern (PF), polymerization depth (PP), flexural strength (RF) and elasticity module (ME) of conventional composite resins with zirconia addition, with addition of zirconia and diatomite and single increment, in restorations made by the semi-direct technique, in two aging times (24h and 6 months). METHODOLOGY: Trunk-cone cavities were created in dentin of bovine incisors (N = 136), for the manufacture of semi-direct restorations using resins: Bulk Fill (BF) (3M ESPE®), Resin Z250 XT (Z250XT) (3M ESPE®), Resin Zirconfill (ZF) (BM4®) and Z350 XT Resin (Z350XT) (3M ESPE®), cemented with RelyX Ultimate self-etching dual resin cement (3M ESPE®). The samples were stored for 24 hours and 6 months in an oven at 37ºC before the RU and PF tests were carried out, and the samples with 24 hours were selected for the PP test. For the RF and ME tests, using a silicone matrix, standard toothpicks (10.0 mm. X 1.0 mm. High x 2.0 mm.) Were made for each tested resin (n = 10) and also stored in an oven at 37ºC for 24h and 6 months before testing. RESULTS: In the immediate analysis, the ZF resin showed the highest RU among the groups and showed a statistically significant difference with the BF group. The Z350 resin increased its RU with the aging time. There was no difference between the RF of the resins analyzed after 24 hours, but after 6 months the Z250 showed the lowest average, while the other groups increased the RF over time, with the greatest increase for the ZF group. Regarding ME, only resins Z350 and ZF showed a statistically significant difference with the aging time of the samples, increasing this value. Mixed fractures were predominant for all composites in both aging times and for PP, no statistically significant differences were found between the study groups. CONCLUSION: The resins that contained added zirconia or zirconia and diatomite in their inorganic content, as well as the single-increment resin showed positive behaviors in relation to the properties of RU, RF and ME, mainly for resins Z350XT and ZF. Clinical studies are recommended to confirm the results of this laboratory study (AU).