Need for Disinfecting New Orthodontic Brackets-A Reality Check

Sowmithra Devi S^1*, Ashwin Mathew George¹ and Rajesh kumar²

^*Correspondence: Sowmithra Devi S, Department of Orthodontics, Saveetha Dental College, Saveetha University, Chennai, India, Email:

Author info »

Introduction

This study was undertaken to find out if the brackets purchased from manufacturers or dealers are proven to be contamination free before using it directly in patients. Is the freshly purchased brackets microbe free to prevent any iatrogenic infection? There is not much evidence available in the literature regarding microbial contamination of freshly purchased brackets. The morphology of brackets is designed in such a way that it can retain plaque. The human oral cavity contains several distinct microbial habitats, such as the teeth, the cheek, the lips, the tongue, the gingiva, the gingival sulcus, and the hard and soft palate [1]. These habitats that act as reservoirs for several pathogenic organisms cause systemic infection and increase the risk of crosscontamination. Introduction of fixed or removable orthodontic appliances in the oral cavity may cause specific variations in the oral microflora by decreasing the pH, increasing the dental plaque accumulation and raising the microbial count in saliva. Further, these changes contribute to the increased risk of cross-contamination. Among all of the microorganisms, gram-positive Staphylococci are considered as the major cause of nosocomial infections. Heat sterilization and disinfection are the effective methods to eliminate microorganisms causing contamination. However, literature has reported chemical disinfection to be more effective in reducing contamination when compared to heat sterilization. Glutaraldehyde, hydrogen peroxide, alcohol, and chlorhexidine are the disinfectants commonly used in the chemical sterilization process [2]. Several in vitro and in vivo studies reported microbial contamination in orthodontic appliances received directly from the manufacturers. However, only a few brands of brackets have been tested for its microbial contamination. Although the instruments used in dental practice are adequatelysterilized, this is not factual for orthodontic appliances, such as brackets, bands, and arch wires. As a responsible clinician, the objective is to break the circle of infection by avoiding contamination [3].

Based on these observations, the present study was conducted to

To evaluate the bacterial load of orthodontic brackets received directly from manufacturers

To assess the efficacy of two commonly used in vitro disinfectants using gluteraldehyde and povidone iodine on the selected brackets after they had been universally contaminated with microflora.

The null hypothesis is that there is no microbial contamination of orthodontic brackets when received from the manufacturer or dealers [4].

Materials and Methods

Ten different brands of brackets were included in this study for testing the microbial contamination (five international and five domestic brands) In this study various other brands were included to assess contamination. All of them were bought from the manufacturers and suppliers and these bracket kits were checked for any damage that could possibly affect the results of the study [5]. This study was carried out in the Nanobiomedicine Lab, Saveetha University. The bracket kits were kept in a laminar airflow chamber to ensure a sterile environment for opening of the bracket kits. Each of the bracket kits were carefully opened inside the laminar airflow chamber and one left premolar bracket from each of the ten bracket kits was carefully withdrawn for testing the microbial contamination using an autoclaved bracket holder.

These brackets were segregated into ten groups that included one left premolar bracket from each brand. All the ten samples were subjected to microbiological tests to evaluate microbial growth. The brackets were immersed individually in a cotton plugged test tube with sterile distilled water and mixed thoroughly for 10 minutes [6].

Each of the test tubes was labelled individually with the brand name that held the respective bracket. A swab of the sterile distilled water with brackets is collected and the organisms were allowed to grow in nutrient agar media and incubated for 24 hours at 37°C evaluate bacterial growth. Bacterial Colonies formed were counted after 24 hours of incubation [7-9].

The second aim of the study was to find out the disinfecting efficacy of two commonly used disinfectants i.e. 2% gluteraldehyde and 10% povidone iodine after being uniformly contaminated with saliva. All of the brackets included for testing the microbial contamination was uniformly contaminated with saliva collected from an orthodontic patient that were found to have both gram positive and gram negative bacterial flora and they were divided into two groups, iodine and gluteraldehyde group. After purposeful contamination of brackets five of the ten contaminated brackets were immersed separately in 10% povidone iodine and the other five contaminated brackets were immersed separately in 2% gluteraldehyde for 10 minutes After 10 mins the brackets were washed with distilled water and mixed thoroughly in a test tube of sterile water for 10 minutes

A swab was taken from each of these test tubes and organisms were allowed to grow in nutrient agar plates, incubating it at 37°C for 24 hrs. After 24 hrs colony forming units were counted (Figure 1-7).

Figure 1: Ten groups of brackets are placed in laminar airflow chamber.

Figure 2: A swab of the thoroughly mixed distilled water with bracket is collected.

Figure 3: The collected swab is cultured in nutrient agar plates.

Figure 4: CFU units were counted at the end of 24 hrs.

Figure 5: One left premolar bracket from 3 M unites gemini was used as the control group.

Figure 6: Each of these brackets were immersed in two commonly used disinfectants-10% povidone iodine and 2% glutaraldehyde for 10 mins.

Figure 7: CFU units were checked after 24 hrs of incubation at 37°C.

Results

Result 1: Assessment of microbial contamination of brackets

After incubation of 24hrs in nutrient agar, Colony forming units were counted for all ten bracket samples.

Colony forming units were found in five manufacturing brands (Table 1). Other five bracket samples were free of any microbial growth.

Table 1: Evaluation of microbial contamination of brackets.