Structural Organization of Dental Biofilm Formed in situ in the Presence of Sucrose Associated to Maltodextrin

Brazilian Dental Journal (2019) 30(1): 36-42 http://dx.doi.org/10.1590/0103-6440201902183 ISSN 0103-6440 Structural Organization of Dental Biofilm Formed in situ in the Presence of Sucrose Associated to Maltodextrin Gabriela Rezende1 ,Rodrigo Alex Arthur1, Marcelo Lazzaron Lamers2, Lina Naomi Hashizume1 Maltodextrins, derived from corn starch, have been added to industrialized food combined with sucrose. However it is not clear the diffusion properties of the dental biofilm matrix and the tridimensional structure of multispecies biofilms formed in the presence of these carbohydrates. Therefore, the aim of study was to investigate by confocal laser scanning microscopy (CLSM) the structural organization of the multispecies dental biofilm formed in situ under exposure to sucrose associated to maltodextrin. Adult volunteers wore an intraoral palatal appliance containing bovine enamel blocks. They were instructed to remove the appliance 8 times per day and drop the following solutions on the enamel blocks: deionized distilled water (DDW), maltodextrin, sucrose + maltodextrin or sucrose. Biofilms formed were stained and the percentage of extracellular polysaccharide (%EPS) and thickness were determined by CLSM. Biofilm formed in the presence of sucrose and sucrose + maltodextrin presented similar %EPS and higher than DDW and maltodextrin. Regarding to the biofilm thickness, sucrose and sucrose + maltodextrin treatments were thicker than DDW and maltodextrin and similar between them. The structural organization of the multispecies dental biofilm formed in situ in the presence of sucrose does not change when this carbohydrate is associated to maltodextrin. Introduction Dental caries is a biofilm-dependent disease associated with frequent intake of a diet rich in rapidly fermented carbohydrates that are converted to acidic end-products by biofilm microbiota. The low pH induced by the fermentation of these carbohydrates disrupts the mineral equilibrium on the tooth surface, biofilm fluid, and saliva leading to tooth mineral loss (1). It has been shown that most dietary carbohydrates, such as glucose, fructose, maltose, and sucrose, do not differ from one another regards to their acidogenic potential. This means that they are fermented at the same rate by dental biofilm bacteria (2). However, the fermentation of sucrose by Streptococcus mutans leads to the production of an insoluble form of polysaccharides that become structurally integrated into the biofilm extracellular matrix. Insoluble extracellular polysaccharides (EPS) synthesized from sucrose is able to enhance the diffusion pattern of acids throughout the biofilm matrix by increasing the porosity of the extracellular matrix. In addition, EPS acts as biological glue that enhances the adherence of microorganisms to each other and to the tooth surface, which increases dental biofilm formation. Therefore, sucrose has been considered as the most cariogenic dietary carbohydrate (3,4). Maltodextrins, which are glucose polymers obtained by hydrolysis of corn starch, have been added to industrialized food as thickening agent and to improve storage properties 1Department of Preventive and Social Dentistry, Faculty of Dentistry, UFRGS - Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil 2Department of Morphological Sciences, Institute of Basic Health Sciences, UFRGS - Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil Correspondence: Lina Naomi Hashizume, Rua Ramiro Barcelos, 2492, 90035-003 Porto Alegre, RS, Brasil. Tel: +55-51-3308-5348. e-mail: Key Words: maltodextrin, sucrose, dental biofilm, dental caries, confocal laser scanning microscopy. and texture of dry products. It is known that the caloric content of industrialized foods, such as infant formulas, dietary supplements, and sports drinks is increased by the addition of maltodextrins (5). Many maltodextrin-based products have also sucrose in the composition. In vivo studies report that the cariogenic potential of starch in association with sucrose is greater than the cariogenic potential of these carbohydrates when consumed alone (6,7). Furthermore, some studies have suggested that the addition of starch would enhance the cariogenic potential of sucrose (8-10). It has also been demonstrated that soy- and milk-based infant formulas containing maltodextrins are potentially cariogenic and that their cariogenic potential increases when supplemented with sucrose (11). However a recent in vitro study investigated the effect of the association of maltodextrin and sucrose on the acidogenicity and adherence of cariogenic bacteria and reported that the addition of maltodextrin to sucrose does not increase the cariogenicity of sucrose in terms of acidogenicity and adherence of the cariogenic bacteria (12). The cariogenic potential of dietary carbohydrates has been determined on in situ studies by traditional methods based on the quantification of tooth mineral loss and the determination of chemical composition of dental biofilms, in terms of calcium, inorganic phosphate, fluoride and EPS concentrations (8,11). A recent in situ study tested if maltodextrin could increase the cariogenic potential of Braz Dent J 30(1) 2019 Material and Methods Experimental Design This study was an in situ, cross-over, randomized, double-blind and split-mouth study. Six adult volunteers wore during 14 days an intraoral palatal appliance containing 2 bovine enamel blocks. They were instructed to drop, 8 times per day, two of the following solutions on the enamel blocks (one solution per enamel block): deionized distilled water, maltodextrin, maltodextrin+sucrose or sucrose. After the experimental period, the biofilms formed were analyzed by CLSM. The percentage of extracellular polysaccharides (%EPS), tridimensional structure, and thickness of the biofilm were determined. The present study randomized the distribution of enamel blocks for each intraoral appliance, the volunteers for each experimental period and the side of the intraoral appliance to apply different solutions in each experimental period. It was used the website Randomization.com (http://www. randomization.com). Subjects Six volunteers (aged 24.33±2.73) participated in this study. The inclusion criteria were as follows: good general and dental health, no receipt of antibiotics during the last 2 months, at least 24 natural teeth, unstimulated salivary flow rate of 0.25-0.35 mL/min and no use of orthodontic appliances. The study protocol was approved by the Research and Ethics Committee of the Federal University of Rio Grande do Sul (protocol number 666.924) and informed consent was obtained from each participant prior to the beginning of the study. Enamel Blocks and Palatal Appliance Preparation Enamel blocks were obtained from bovine incisors previously stored on 2% buffered formaldehyde solution (pH 7.0) during 30 days. Teeth presenting fractures on the external enamel surface, as well as (...truncated)