A Abstractbackground: cross-infection in dental healthcare facilities may occur due to bacterial contamination on dental unit surfaces that are not properly maintained. identifying bacteria present in the clinical working environment is essential to understand potential microorganisms capable of persisting in dental settings and to evaluate their possible antimicrobial resistance. currently, data regarding bacterial contamination on the dental units of the hortensia integrated clinic (kih) at the dental and oral hospital, faculty of dentistry, trisakti university, are still limited. objective: this study aims to determine the bacterial isolates found on dental unit surfaces at kih rsgm fkg usakti and to evaluate their potential resistance based on morphological characteristics and molecular examination. methods: this descriptive observational study with a cross-sectional design utilized purposive sampling from several dental unit surfaces. bacterial isolation was performed using selective media (emb, msa, and mrs). colony morphology was observed, followed by molecular analysis using polymerase chain reaction (pcr) with universal lactobacillus sp. primers and lactobacillus casei–specific primers. pcr products were analyzed using agarose gel electrophoresis. the absence of a positive control limits the pcr results to supporting evidence for suspicion rather than definitive identification. results: no target-appropriate colony growth was observed on emb or msa media, while mrs agar produced dominant colonies consistent with lactic acid bacteria. pcr using universal lactobacillus sp. primers showed no amplification, whereas the l. casei specific primers produced a single band of 227 bp. based on colony morphology and this amplification pattern, the isolate is suspected to be lactobacillus casei. antibiotic susceptibility testing was not continued; however, literature indicates that lactobacillus species possess intrinsic resistance mechanisms to several antibiotics. conclusion: the bacterial isolate obtained from dental unit surfaces at kih rsgm fkg usakti is suspected to be lactobacillus casei based on colony morphology and pcr amplification in the absence of a positive control. although categorized as a commensal organism, its potential intrinsic resistance highlights the need for consistent dental unit hygiene and regular monitoring to minimize cross-infection risks.keywords: lactobacillus casei, dental unit, antibiotic resistance, pcr, contamination