25 February 2022

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Microbial contamination of resin composites inside their dispensers: An increased risk of cross-infection?

Authors: Allegra Comba, Federica Florenzano

Lorenzo Breschi

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Cross-contamination control in the dental setting is always an actual topic for the heathcare of the workers and for the biosafety of the patients. Saliva and dental plaque can be considered sources of cross-infection. The effects of microorganisms’ contamination of different types of resin-based composites (RBCs) inside the dispensing syringes was investigated by Mazzitelli et al.

Materials and methods
The study was developed in two parts: an elettronic survey submitted via Google forms to Italian dentists and a second part with a bench test performed to evaluate the microbial viability on the surfaces of this different composites with/out photocuring. For the latter, 3 nanohybrid RBCs differing in matrix chemistry and fillers were used: FiltekTM Supreme XTE (3MTM); Venus Pearl (Kulzer GmbH); Admira Fusion x-tra (Voco).  Uncured RBCs were exposed to standardized inocula of Streptococcus Mutans, Candida Albicans, Lactobacillus Rhamnosus, or mixt in an in vitro model reproducing clinical restorative procedures. Half of the RBCs specimens were cured after exposure. Microbial viability was assessed using an MTT- based test. Statistical analysis included three-way ANOVA and Tukey’s tests (p<0.05).

Results
Of the 700 questionnaires sent, a total of 300 dentists completed the survey. Most of dentists declared to use the spatula to carry the RBCs from the syringe to the dental cavity (50% same spatula; 35% two spatulas). However, 80% of respondents had personal feelings that using one spatula could be a source of cross-contamination . 

In vitro results using one spatula showed microbial contamination of all RBCs after one hour of storage. The contamination levels depended on the used strain  and RBC type  (p<0.0001), but photocuring did not reduce contamination (p = 0.2992).

Conclusion
Dentists should be aware in handling composite materials during restorative procedures as mismanipulation may expose to cross-contamination effects. 

For additional information: Microbial contamination of resin composites inside their dispensers: An increased risk of cross-infection?