In Vitro Testing of Botanical Extracts as Safe and Effective Alternatives for Oral Care: A Two-Pronged Model Integrating Pathogen Control and Host Compatibility

Background: Commercial oral care products commonly incorporate synthetic antimicrobials such as cetylpyridinium chloride (Cetyl Cl.), L-Arginine (L-arg.), and stannous fluoride (SnF2). Although effective against oral pathogens, these agents are often associated with adverse effects including mucosal irritation, taste alteration, and disruption of the oral microbiome. These limitations have spurred growing interest in safer, plant-based alternatives. In this study, we present a two-pronged in vitro oral care testing model that integrates cell assays with machine-guided quantitative microscopy analyses to assess both antibacterial efficacy and host biocompatibility of botanical extracts. Methods: Using Miswak (Salvadora persica) and Neem (Azadirachta indica) as representative natural products, we conducted antibacterial and antibiofilm testing including the evaluation of the minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC), alongside biocompatibility assessments via MTT cell viability assays on probiotic bacteria and mammalian oral cells. To evaluate biofilm structure and disruption, we employed scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), augmented with machine-guided Weka segmentation and automated image analysis. Results: Our findings show that Miswak and Neem extracts exhibited 75–100% antibacterial and antibiofilm efficacy against all tested bacteria, as demonstrated by cell assays and microscopy analyses, comparable to synthetic oral care agents. They also maintained ~100% viability toward commensal microbes and mammalian oral cells, whereas Cetyl Cl. and SnF2 showed dose-dependent cytotoxicity. Conclusions: This dual-assessment oral care testing model provides a comprehensive and biologically relevant framework for the discovery and screening of safe and effective natural herbal extracts in oral care applications.