# In Vitro Activity of Caffe Acid Phenethyl Ester against Different Oral Microorganisms
## 4 Discussion  
One of the most common worldwide dental problems is dental caries. Dental caries starts with dental plaque formation that leads to cariogenic bacteria colonization. In previous years, numerous studies have been carried out to try and control dental caries by inhibiting bacterial growth, as well as bacterial colonization. Many clinical studies have proven the direct and indirect relationship between cariogenic bacteria and systemic diseases such as peritonitis, atherosclerosis, ulcerative colitis, and infective endocarditis [19, 20]. Recently, a variety of organic natural materials have been tested in vitro to prevent cariogenic bacterial growth [9]. Furthermore, organic materials have been employed as remedies for thousands of years due to their ease of accessibility, extraction, and use [21]. Propolis is a natural material synthesized by bees to disinfect the hive. The antimicrobial effect of propolis has been investigated extensively in the medical field. Many cultures have used propolisis extract (caffeic acid phenethyl ester) for many years due to its significant effects in different areas of medicine [22]. A review of the literature has shown  
Figure 1: Viable bacterial count using Log10 transformation CAPE (caffeic acid) vs. NaF (sodium fluoride). many studies proving the antibiotic potency of CAPE against various bacteria. It has been proposed that CAPE can modify the dental pellicle favorably to prevent or even reverse the process of caries by eliminating the cariogenic bacteria. Propolis and its extract (CAPE) have many benefits in managing multiple pathogens such as bacterial, fungal and viral infections, cancer, and inflammatory diseases [23]. The results of this study displayed a promising effect of propolis in terms of antibacterial activity against four different types of bacteria. The minimal bactericidal concentration (MBC) and minimal inhibitory concentration (MIC) are the gold standards for evaluating an agent's antimicrobial efficacy against bacteria and are thus used to appraise alternative antimicrobial evaluation procedures [24]. Interestingly, CAPE showed promising effects in preventing the growth and flourishing of oral bacteria. The null hypothesis was disproved since CAPE was most effective against _S. oralis_, _S. mutans_ had a MIC of 1 mg/mL and MBC of 1.5 mg/mL, and _S. salivarius_ and _S. aureus_ had a MIC of 3 mg/mL and MBC of 4 mg/mL. When employing the control NaF, all tested microorganisms showed a slightly similar resistance pattern, with _S. mutans_ and _S. oralis_ exhibiting the least resistance and _S. aureus_ and _S. salivarius_ exhibiting the greatest. The differing reports on the chemical nature and antimicrobial ability of the propolis extract, specifically CAPE, and the significant antimicrobial activity presented in the current results, incited systematic chemical characterization and antibacterial testing to categorize the antimicrobial components present, and to further investigate their properties for possible use as therapeutic antimicrobials [25; 26]. In fact, one of the microorganisms that causes tooth caries is _S. mutans_. In an earlier investigation, while the role of _S. salivarius_ is more apparent in active carious lesions, it aids in the progression of caries in the teeth [27]. This study's findings are consistent with prior studies that have found CAPE to be bactericidal as well as growth-inhibiting for all cariogenic bacteria [28; 29]. Furthermore, _S. oralis_ was found to be the dominant microorganism in the active carious lesion. It is thought to play a role in the progression and long-term viability of the caries' progression [25; 28]. The findings are in line with a study that found _S. salivarius_, _S. aureus_, and _S. mutans_ to be sensitive to CAPE, with substantial MIC and MBC values [26; 28]. Previous studies have proven that CAPE is safe even in relatively large doses. Additionally, evidence has shown that CAPE is concentration dependent. For instance, at a CAPE dosage of 100 mg/mL, _S.