OBJECTIVE: The present study analyzed xylitol concentrations in artificial saliva over time after application of varnishes containing 10% and 20% xylitol. MATERIAL AND METHODS: Fifteen bovine enamel specimens (8x4 mm) were randomly allocated to 3 groups (n=5/group), according to the type of varnish used: 10% xylitol, 20% xylitol and no xylitol (control). After varnish application (4 mg), specimens were immersed in vials containing 500 µL of artificial saliva. Saliva samples were collected in different times (1, 8, 12, 16, 24, 48 and 72 h) and xylitol concentrations were analyzed. Data were assessed by two-way repeated-measures ANOVA (p<0.05). RESULTS: Colorimetric analysis was not able to detect xylitol in saliva samples of the control group. Salivary xylitol concentrations were significantly higher up to 8 h after application of the 20% xylitol varnish. Thereafter, the 10% xylitol varnish released larger amounts of that polyol in artificial saliva. CONCLUSIONS: Despite the results in short-term, sustained xylitol releases could be obtained when the 10% xylitol varnish was used. These varnishes seem to be viable alternatives to increase salivary xylitol levels, and therefore, should be clinically tested to confirm their effectiveness.

Dental amalgam residues are probably the most important chemical residues generated from clinical dental practice because of the presence of heavy metals among its constituents, mainly mercury and silver. OBJECTIVE: The purpose of this study was to develop an alternative method for the recovery of silver residues from dental amalgam. MATERIAL AND METHODS: The residue generated after vacuum distillation of dental amalgam for the separation of mercury was initially diluted with 32.5% HNO3, followed by precipitation with 20% NaCl. Sequentially, under constant heating and agitation with NaOH and sucrose, the sample was reduced to metallic silver. However, the processing time was too long, which turned this procedure not viable. In another sequence of experiments, the dilution was accomplished with concentrated HNO3 at 90ºC, followed by precipitation with 20% NaCl. After washing, the pellet was diluted with concentrated NH4OH, water and more NaCl in order to facilitate the reaction with the reducer. RESULTS: Ascorbic acid was efficiently used as reducer, allowing a fast reduction, thus making the procedure viable. CONCLUSIONS: The proposed methodology is of easy application and does not require sophisticated equipment or expensive reagents.

Mercury, as any other heavy metal, may cause environmental damages due to its accumulation and biotransformation. Dental offices, whether private or institutional, use dental amalgam as a restorative material on a daily basis. Dental amalgam is composed of mercury (50%), silver (30%) and other metals. Approximately 30% of the amalgam prepared in dental offices (0.6 g per capsule) are wasted and inadequately discarded without any treatment. Methods for mercury recovery have been proposed previously, using high temperatures through exposure to direct flame (650°C), long processing time, and hazardous reagents as potassium cyanide. The purpose of this study was to develop a method to replace the direct flame by an electrical mantle in the process of mercury recovery. Results showed an average mercury recovery of 90% from 2 kg of amalgam after 30 minutes of processing time, thus optimizing the procedure. The proposed modifications allowed a significant reduction in processing time and a mercury recovery with high purity. The modified process also provided minimization of operator exposure to physical, chemical and ergonomic hazards, representing a technological advance compared to the risks inherent to the original method. It also provided environmental health and economy of energy resources by replacing a finite energy source (fossil and organic) by a more environmentally appropriate electric source, resulting in significant improvement of the procedure for mercury recovery from dental amalgam.

Chocolates em barra e bolachas de chocolate são guloseimas altamente apreciadas pelas crianças. A possibilidade de conter flúor (F) em seus componentes, associada a seu excessivo consumo podem torná-los contribuintes decisivos para a ingestão diária total de F. Assim, eles poderiam participar no estabelecimento da fluorose dental. O objetivo deste estudo foi analisar a concentração de flúor [F] dos chocolates em barra (CB) Baton, Confeti, Garoto Ball, Kinder Ovo, M&M’s, Milkybar, Nescau, Nescau Ball, Surpresa, Surpresa Bichos, Tortuguita; e das bolachas de chocolate (CC) Danyt’s, Hipopó, Nescau, Passatempo, Pokémon, Sítio do Pica-Pau Amarelo e Trakinas. Os produtos foram adquiridos em Bauru, São Paulo, Brasil. Três gramas de cada produto foram previamente calcinadas a uma temperatura de 525°C (CB e recheio das bolachas), e de 550°C (massas das bolachas), durante 4 horas. O F foi separado das cinzas por difusão facilitada por hexametildisiloxano (HMDS). As análises de F foram feitas com o eletrodo específico. As [F]s médias ± DP e amplitude (mg/g) foram: CB = 0,30 ± 0,45 (0,07 - 1,60, n = 12) e CC = 1,08 ± 2,64 (0,04 - 7,10, n = 7). Concluiu-se que alguns dos alimentos analisados podem ser importantes contribuintes para a ingestão diária total de F. No caso do produto que apresentou a maior [F] (Danyt’s), quando apenas 3 unidades são consumidas uma única vez ao dia, elas podem fornecer mais de 40% da ingestão diária máxima de F recomendada (0,07 mg/kg peso corporal) para uma criança de 2 anos de idade (12 kg). A [F] presente nesses produtos deveria ser informada em seus rótulos.

Chocolate bars and chocolate cookies are foodstuffs highly appreciated by children. The possibility of having fluorine (F) among their components, associated with an excessive consumption, may make them decisive contributors to the total daily F intake. Thus, they could participate in the establishment of dental fluorosis. The aim of this study was to analyze the fluorine concentration [F] of the chocolates bars (CB) Baton, Confeti, Garoto Ball, Kinder Ovo, M&M’s, Milkybar, Nescau, Nescau Ball, Surpresa, Surpresa Bichos, Tortuguita; and of the chocolate cookies (CC) Danyt’s, Hipopó, Nescau, Passatempo, Pokémon, Sítio do Pica-Pau Amarelo and Trakinas. Samples were purchased in Bauru, São Paulo, Brazil. Three grams of each product were previously ashed at 525°C (CB and cookies fillings) and at 550°C (cookies dough), during 4 hours. Fluorine was separated from the ash by hexamethyldisiloxane (HMDS)-facilitated diffusion. Fluorine analysis was carried out with the specific electrode. Mean [F]s ± SD and amplitude (unit mg/g) were: CB = 0.30 ± 0.45 (0.07 - 1.60, n = 12) and CC = 1.08 ± 2.64 (0.04 - 7.10, n = 7). It was concluded that some of the analyzed foods may be important contributors to the total daily F intake. As for the product that had the highest [F] (Danyt’s), when only 3 units are consumed just once a day, they may supply up to 40% of the maximum recommended daily F intake (0.07 mg/kg body weight) for a 2-year-old child (12 kg). The [F] in these products should be informed on their labels.