Microbiological models for accelerated development of secondary caries in vitro

Area of Science:

• Dental Materials Science
• Microbiology
• Biomaterials Engineering

Background:

• Secondary caries remains a significant challenge in restorative dentistry.
• Developing reliable in vitro models for secondary caries is crucial for evaluating dental materials.
• Existing models may not fully replicate clinical conditions for caries development.

Purpose of the Study:

• To compare the efficacy of open-cycle versus closed-cycle in vitro microbiological models for secondary caries.
• To assess the secondary caries development around resin-based composite (RBC) and resin-modified glass-ionomer cement (RMGIC) restorations.
• To evaluate the caries-protective properties of RMGIC compared to RBC in an accelerated in vitro setting.

Main Methods:

• Standardized class II cavities in human molars were restored with RBC and RMGIC.
• Secondary caries was induced using Streptococcus mutans biofilms in either open-cycle or closed-cycle bioreactors.
• Micro-computed tomography (micro-CT) was used to quantify demineralization depths before and after biofilm exposure.

Main Results:

• Both open and closed systems successfully induced secondary caries in vitro.
• The open-cycle system demonstrated significantly greater overall demineralization depths.
• RMGIC exhibited significantly lower demineralization depths adjacent to restorations in the open system compared to RBC.

Conclusions:

• The open-cycle bioreactor system effectively simulates secondary caries development and material performance.
• This model validates the caries-protective effect of RMGIC over RBC, aligning with clinical observations.
• Accelerated in vitro models are essential for predicting the long-term behavior of dental restorative materials.