Microbial Colonization of Conventional and Enhanced Elastomeric Chains in Orthodontic Patients

Review Article

Austin J Dent. 2015;2(2): 1017.

Microbial Colonization of Conventional and Enhanced Elastomeric Chains in Orthodontic Patients

Mattos CT1, Baratieri C2, Freitas AOA3, Alviano DS4, Souza MMG3, Araújo MTS3, Nojima LI3, Nojima MCG3*

1Dental Clinics Department, Universidade Federal Fluminense, Brazil

2Department of Orthodontics, Universidade Federal de Santa Catarina, Brazil

3Department of Pediatric Dentistry and Orthodontics, Universidade Federal do Rio de Janeiro, Brazil

4Paulo de Góes Institute of Microbiology, Universidade Federal do Rio de Janeiro, Brazil

*Corresponding author: Nojima MCG, Departamento de Ortodontia, Faculdade de Odontologia, Universidade Federal do Rio de Janeiro, Av. Professor Rodolpho Paulo Rocco, 325, Ilha do Fundão, Rio de Janeiro, RJ, CEP: 21941-617, Brazil

Received: September 25, 2014; Accepted: February 23, 2015; Published: February 25, 2015


The aim of this study was to evaluate microbial contamination of enhanced elastomeric chain (Super Slick, Metafisica technology, TP Orthodontics) compared to a conventional chain in situ. Twenty-six segments of elastomeric chains were placed in thirteen patients attached to their archwires. After 21 days, the chains were retrieved and their biological material was submitted to microbiological processing and cultured in nonspecific media and in media specific to detect Streptococcus spp, Lactobacilli spp and Candida spp. The number of Colony Forming Units (CFU) was macroscopically counted. Elastomeric chains were weighed for quantification of the mass of accumulated plaque. The results of colony counting were described with frequencies and analyzed with the Wilcoxon test. Statistical analysis showed no differences between the chains in number of CFUs on any medium tested. Streptococcus spp were observed on 61.5% of conventional chains and on 41.7% of Super Slick chains. The mean difference between the initial and final weight of the chains was 0.0030 g for conventional chains and 0.0031 g for Super Slick chains. The elastomeric chains had similar bacterial colonization and plaque accumulation properties. Further investigations are needed before these modified chains be considered an accessory with less bacterial biofilm formation.

Key words: Orthodontics; Microbiology; Elastomers


The placement of orthodontic appliances increases dental biofilm accumulation [1] and favors Streptococcus mutans colonization [2]. The adoption of strict measures for maintenance of oral health during orthodontic therapy has become more justifiable in view of current concepts of health promotion and biosecurity.

The aim of orthodontic bacterial adhesion research is to prevent the formation of plaque on orthodontic materials [3]. Orthodontic materials with modified properties that are claimed to provide greater efficacy in controlling bacterial development on their surfaces have been introduced [4].

Elastomeric chains are widely used in Orthodontics, especially in space closure, in the retraction of anterior teeth and in the correction of rotations. However, they can act as a potential host for microbial accumulation [5].

Coating elastomeric chains with a hydrophobic polymeric substance has been suggested as a methodology in decreasing friction at the archwire-bracket interface and in repelling salivary adherends. They also provide good retention, tensile strength and better elastic properties [5]. The Metafasix technology (TP Orthodontics, LaPorte, Ind), used in the Super Slick elastomeric chain (TP Orthodontics, LaPorte, Ind), is a water-insoluble, hidrogel-polymer coating that transforms the polyurethane-based elastomeric surface into a highly smooth surface when moistened. As a consequence, less accumulation of bacterial biofilm on the chain surface during orthodontic therapy is expected [4].

There are no published studies assessing microbial contamination on the surface of elastomeric chains modified by Metafasix technology compared to conventional elastomeric chains submitted to the oral environment.

Therefore the aim of the present study was to evaluate the microbial contamination in situ of Super Slick elastomeric chain compared to a conventional chain exposed to the oral environment for 21 days. The null hypothesis raised is that there would be no difference in microbial contamination of Super Slick elastomeric chain and the conventional one.

Material and Methods

A sample size calculation was made in order to detect a significant difference with a power value of 80% and a significance level of 5%, which indicated twelve patients, according to the study design adopted.

Thirteen patients of both genders, aged 17 to 30 years, who were undergoing orthodontic treatment with fixed standard edgewise appliance in the finishing stage and with rectangular archwires in both arches, were selected from the orthodontic clinic of the Post-graduation course of the Faculty of Dentistry of the Federal University of Rio de Janeiro. Individuals who had any systemic disease or periodontal disease, patients who had used antibiotics within the previous three months and in current use of antimicrobial mouthwashes were excluded from the study. This research project was approved by the local Ethics in Research Committee and written informed consent was obtained from the patients or their respective parents.

In each volunteer, two quadrants of the mouth were randomly chosen using random number tables. The generator of the tables and the researcher who placed the chains were different individuals (CB and CTM). Two crimpable hooks 18 mm apart from each other were attached to the archwires in the interbracket region in the quadrants selected. A Super Slick elastomeric chain (size, mini; clear color; TP Orthodontics, LaPorte, Ind, USA) was stretched in one quadrant supported by the hooks and an aesthetic conventional elastomeric chain (size, short; pearl color; American Orthodontics, Sheboygan, Wis, USA) was stretched in the other quadrant chosen. Both elastomeric chains used had an equal number of five loops. A pilot study showed that the use of five loops of these two specific elastomeric chains of the size mentioned in the specified distance produced a similar force. The mean force produced by the Super Slick elastomeric chain was 176.85 g and the mean force produced by the conventional chain was 171.54 g. The force was measured on the EMIC DL 10000 universal testing machine (São José dos Pinhais, Brazil).

The volunteers were oriented on oral hygiene performance. They were supplied with the same toothbrush (Colgate Professional Extra Clean, Colgate-Palmolive, São Paulo, Brazil) and toothpaste (Cogate Total 12, Colgate-Palmolive, São Paulo, Brazil), and asked to use them for oral hygiene during the period of the trial and to refrain from any other oral hygiene products. The volunteers were also asked to maintain the dietary habits recommended by the clinic of the Postgraduate Course in Orthodontics.

The biological material was collected and processed by one trained and calibrated researcher, who performed every microbial test. After 21 days, the elastomeric chains were carefully removed and stored individually in Eppendorf tubes. Each tube containing an elastomeric chain was weighed on high precision scales (Shimadzu, São Paulo, and São Paulo). One milliliter of sterile saline (0.85% sodium chloride) was added in each tube so that the material could be used for subsequent cell culture. The interval between collection and transportation of material for cell culture was less than 2 hours. The tubes containing the biological material were vortexed for 30 seconds. The resulting suspension was further diluted to 10-2 and 10-3 in sterile saline. Solid culture media were used for nonspecific analysis (Brain Heart Infusion – BHI) and for specific analysis to detect Streptococcus spp (Mitis salivarius), Lactobacilli spp (Rogosa) and Candida spp (CHROMagar). The biological material was inoculated onto Petri plates. The 10-3 dilution was used on the BHI and on the Mitis salivarius media and the 10-2 dilution on the Rogosa and CHROMagar media. These dilutions were chosen based on a pilot study. Streptococcus spp incubation was done with oxygen restriction and nonspecific, Lactobacilli spp and Candida spp were cultured without oxygen restriction. The Petri dishes were maintained at 37° C inside a heater for 24 hours, except for the CHROMagar medium, which was kept in the heater for 48 hours to allow microbial growth. The identification and counting of colonies were done macroscopically. The number of viable microorganisms was calculated from the number of Colony Forming Units (CFU).

After cell culture procedures, the elastomeric chains were washed three times inside the Eppendorf tubes with Phosphate Buffered Saline Solution (PBS) and the tubes were stored in a heater at 37° C with the lid open for 24 hours to allow them to dry. Then the tubes containing the chains were weighed again in order to compare plaque accumulation on the elastomeric chains. The difference between the two weighings was computed for each elastomeric chain in order to quantify the mass of the plaque accumulated on the chains. The same blind researcher did all microbiological procedures.

The results of colony counting were described with frequencies and analyzed statistically with the Wilcoxon nonparametric test at the 5% significance level. All statistical analyses were performed using GraphPad Prism statistical software for Windows (version 4.0, GraphPad Software, San Diego, Calif).


One Super Slick chain of one patient had been lost when she came for the second visit in order to have the elastomeric chains removed.

Microbial analyses showed nonspecific microorganisms on 60% of all elastomeric chains. Their presence was found on 69.3% of the conventional chains and on 49.8% of Super Slick chains. Streptococcus spp were observed on 52% of all elastomeric chains, more specifically on 61.6% of the conventional chains and on 41.6% of Super Slick chains. Lactobacilli spp were not found on any chains. One colonyforming unit of Candida spp was observed on two conventional chains and in one Super Slick chain. Table 1 shows the frequency in valid percent of the number of CFU for each media tested. Figure 1 shows the comparison between conventional and Super Slick elastomeric chains in the distribution of CFUs counted on the BHI and on the Mitis salivarius media.

Citation: Mattos CT, Baratieri C, Freitas AOA, Alviano DS, Souza MMG, et al. Microbial Colonization of Conventional and Enhanced Elastomeric Chains in Orthodontic Patients. Austin J Dent. 2015;2(2): 1017. ISSN:2381-9189