Microbiological models for accelerated development of secondary caries in vitro

Andrei C Ionescu; Sebastian Hahnel; Paolo Delvecchio; Nicoleta Ilie; Marioara Moldovan; Vanessa Zambelli; Giacomo Bellani; Eugenio Brambilla

doi:10.1016/j.jdent.2022.104333

Microbiological models for accelerated development of secondary caries in vitro

J Dent. 2022 Dec:127:104333. doi: 10.1016/j.jdent.2022.104333. Epub 2022 Oct 17.

Authors

Andrei C Ionescu¹, Sebastian Hahnel², Paolo Delvecchio³, Nicoleta Ilie⁴, Marioara Moldovan⁵, Vanessa Zambelli³, Giacomo Bellani³, Eugenio Brambilla⁶

Affiliations

¹ Oral Microbiology and Biomaterials Laboratory, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Milan, Italy. Electronic address: andrei.ionescu@unimi.it.
² Clinic of Prosthodontics and Dental Materials Science, University of Leipzig, Leipzig, Germany; Department of Prosthetic Dentistry, Regensburg University Medical Center, Regensburg, Germany.
³ School of Medicine and Surgery, Università degli Studi di Milano Bicocca, Monza, Italy.
⁴ Department of Conservative Dentistry and Periodontology, University Hospital, Ludwig-Maximilians-University, Munich, Germany.
⁵ Raluca Ripan Institute of Chemistry, Babes-Bolyai University, Cluj-Napoca, Romania.
⁶ Oral Microbiology and Biomaterials Laboratory, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Milan, Italy.

PMID: 36257513
DOI: 10.1016/j.jdent.2022.104333

Abstract

Objectives: The current study aimed to compare the efficacy of two in vitro microbiological models based on open and closed systems designed to obtain secondary caries in an accelerated and reproducible way.

Methods: A conventional resin-based composite (RBC - Majesty ES-2; Kuraray, Japan) and a resin-modified glass-ionomer cement (RMGIC - Ionolux; VOCO, Germany) were used to restore standardized class II cavities (n = 4/tooth, cervical margin in dentin) in 16 human molars. The ability to produce secondary caries with Streptococcus mutans biofilms was tested using either an open-cycle or closed-cycle bioreactor (n = 8 specimens/model). Specimens were scanned before and after the biofilm exposure using micro-CT (Skyscan 1176, 9 µm resolution, 80 kV, 300 mA). Image reconstruction was performed, and demineralization depths (µm) were evaluated at the restoration margins and a distance of 1.0 mm.

Results: Dentin demineralization could be observed in all specimens, and enamel demineralization in 50% of the specimens. The open system bioreactor produced lesions with significantly higher overall demineralization depths (p < .001). However, demineralization depths at a 1.0 mm distance from the restoration margins showed no difference between open and closed systems or materials. In the open system, significantly lower demineralization depths were observed in proximity to RMGIC than RBC (p < .001), which was not significantly different in the closed system (p = .382).

Conclusions: Both systems produced in vitro secondary caries in an accelerated way. However, the open-cycle bioreactor system confirmed the caries-protective activity exerted by the RMGIC material in contrast to the RBC, better simulating materials' clinical behavior.

Clinical significance: The possibility of obtaining accelerated and reproducible secondary caries development in vitro is fundamental in testing the behavior of conventional and yet-to-come restorative dental materials. Such systems can provide faster outcomes regarding the performance of dental restorative materials compared to clinical studies, notwithstanding the importance of the latter.

Keywords: Bioreactor; Caries model; Micro-CT; Secondary caries; Streptococcus mutans.

MeSH terms

Composite Resins
Dental Caries Susceptibility
Dental Caries* / microbiology
Dental Restoration, Permanent / methods
Glass Ionomer Cements
Humans
Tooth Demineralization* / microbiology

Substances

Composite Resins
Glass Ionomer Cements