Microbiology is required by virtually every CODA-accredited dental hygiene program in the United States, and it’s the most directly relevant biology prerequisite to the actual work of a dental hygienist. The reason: the oral cavity hosts more than 700 species of bacteria, and almost every condition a dental hygienist treats — from gingivitis and periodontitis to dental caries to oral candidiasis — is fundamentally a microbiological problem. Programs need entering students to already understand bacterial structure, biofilm formation, antibiotic mechanisms, and infection control before stacking dental-specific microbiology on top.
This guide explains exactly why CODA-accredited dental hygiene programs require microbiology, what specific content the course must cover, what to look for when choosing a microbiology course (including the lab requirement that trips up many applicants), and how to satisfy the requirement efficiently — whether you’re starting from scratch or refreshing expired coursework.
| Quick answer: microbiology requirement for dental hygiene• Required by: Virtually every CODA-accredited dental hygiene program in the United States• Credits: 4 credits (3-credit lecture + 1-credit lab), occasionally 4–5 credits as a combined course• Lab requirement: Universal — almost no CODA programs accept microbiology coursework without a lab component• Recency: Most programs require microbiology completed within 5–7 years of application; some allow up to 10 years• Minimum grade: Most programs require a C; competitive programs require B or B+; some require B+ specifically in microbiology• Why it’s required: CODA Standard 2-8b mandates microbiology content in the dental hygiene curriculum; programs require the prerequisite to ensure students enter prepared |
Of all the biology prerequisites required for dental hygiene admission, microbiology is the one most directly tied to the daily work of the profession. Dental hygienists don’t just clean teeth — they manage a dynamic microbial ecosystem inside every patient’s mouth. Every scaling and root planing procedure is, fundamentally, a microbiological intervention: removing biofilm, disrupting bacterial colonies, and resetting the oral microbiome toward a healthier composition.
The numbers behind this are striking. The oral microbiome contains more than 700 distinct bacterial species, making it the second most diverse microbial community in the human body after the gut. A single milligram of dental plaque contains hundreds of millions of bacterial cells. The dynamic between bacterial species — which ones dominate, which ones are kept in check, how they interact in biofilms — determines whether a patient develops dental caries, periodontal disease, or maintains oral health.
Dental hygienists need to understand:
None of this content can be taught from scratch in a 2-year associate’s program. The CODA-accredited curriculum assumes you arrive already understanding bacterial cell structure, gram staining, antibiotic mechanisms, and the immune response — and then layers oral microbiology, infection control, and clinical microbiology on top. Without the prerequisite, the dental microbiology content becomes incomprehensible.
The Commission on Dental Accreditation (CODA) sets the curriculum standards every accredited dental hygiene program must meet. The relevant standard for microbiology is CODA Standard 2-8b, which specifies the biomedical sciences content that every dental hygiene program must cover.
The full text of Standard 2-8b requires biomedical content in: “anatomy, physiology, chemistry, biochemistry, microbiology, immunology, general and maxillofacial pathology and/or pathophysiology, nutrition and pharmacology.”
Microbiology and immunology appear together in the standard for a reason: dental hygiene practice constantly intersects with the immune system. Periodontal disease is, at its core, a destructive immune response to bacterial dysbiosis. HIV, hepatitis B, and hepatitis C transmission risk shapes every aspect of dental infection control protocols. Patients on immunosuppressive medications require modified treatment plans because their bodies cannot mount normal responses to oral pathogens.
Programs satisfy the CODA Standard 2-8b microbiology and immunology requirement in two ways: (1) by requiring a prerequisite microbiology course before admission, which establishes the foundational content, and (2) by delivering oral microbiology, infection control, and clinical microbiology content during the program itself, building on the prerequisite. Almost no programs try to teach microbiology from scratch during the program — the curriculum is too packed with dental-specific content to make that workable.
| Note: brief variations in CODA standard numberingSome sources reference “CODA Standard 2-9” for biomedical content; the current Accreditation Standards for Dental Hygiene Education Programs places this content under Standard 2-8b. CODA periodically renumbers and revises standards — the most recent significant revision was implemented in 2022, with subsequent amendments in 2023 and 2025. The substantive requirement (mandatory microbiology content in the curriculum) has been stable across all recent revisions. |
Not all microbiology courses are created equal. A 4-credit microbiology course intended for biology majors might emphasize industrial fermentation, environmental microbiology, or evolutionary microbiology — content that has limited applicability to dental hygiene. The microbiology courses that work best as dental hygiene prerequisites focus on pathogenic microbiology and are sometimes labeled “Microbiology for Health Sciences” or “Medical Microbiology.”
The core content that any acceptable dental hygiene microbiology prerequisite should cover:
Bacterial structure and physiology
Cell wall composition (gram-positive vs. gram-negative), cell membrane structure, capsules and pili, bacterial growth phases, oxygen requirements (aerobic, anaerobic, facultative), and binary fission. This content explains why Porphyromonas gingivalis — a strict anaerobe — thrives in deep periodontal pockets but cannot survive on a freshly cleaned tooth surface.
Microbial classification and identification
Gram staining technique, bacterial morphology (cocci, bacilli, spirochetes), biochemical testing, and modern molecular identification methods including 16S rRNA sequencing. Dental hygienists routinely encounter Streptococcus species (gram-positive cocci), Treponema denticola (a gram-negative spirochete), and Lactobacillus species (gram-positive bacilli) — and need to recognize them by morphological category.
Microbial genetics and antibiotic resistance
Plasmids, conjugation, transformation, transduction, and the mechanisms by which antibiotic resistance spreads. This content underlies modern dentistry’s increasingly cautious approach to prophylactic antibiotic use — reducing antibiotic exposure where possible to slow the emergence of resistant oral pathogens.
Host-pathogen interactions and the immune response
Innate immunity (skin barriers, neutrophils, complement), adaptive immunity (T cells, B cells, antibodies), inflammation as a host defense mechanism, and the immune dysregulation that underlies chronic periodontitis. The CODA-accredited dental hygiene curriculum spends substantial time on the immunology of periodontal disease, which is incomprehensible without the foundational prerequisite content.
Major pathogen groups
Bacterial pathogens (with emphasis on those relevant to oral health and aerosol-borne transmission), viruses (especially the herpesviruses, hepatitis viruses, HIV, and HPV — all directly relevant to dental practice), fungi (including Candida albicans, which causes oral thrush), and protozoa. The Candida content alone justifies microbiology as a prerequisite — denture stomatitis and oral thrush are extremely common findings dental hygienists must recognize and counsel patients about.
Sterilization, disinfection, and infection control
Spaulding’s classification (critical, semi-critical, non-critical instruments), autoclave principles, chemical sterilants, high-level disinfection, and CDC infection control guidelines for dental settings. This content connects directly to the National Board Dental Hygiene Examination (NBDHE), which tests sterilization and infection control extensively.
Almost every CODA-accredited dental hygiene program requires the microbiology prerequisite to include a lab component. This is one of the easiest places for applicants to make a costly mistake — enrolling in a 3-credit lecture-only microbiology course because it’s cheaper or faster, then discovering at application time that it doesn’t satisfy the prerequisite.
The reason CODA programs insist on a lab: dental hygiene is a hands-on, procedure-driven profession. Programs need evidence that you can:
These are the same fundamental laboratory skills you’ll use throughout your dental hygiene education — proper handling of contaminated instruments, aseptic technique during patient care, microscopic interpretation of plaque samples, and following established protocols. A lecture-only microbiology course doesn’t demonstrate any of these skills.
What programs look for on the transcript
When admissions committees evaluate your transcript, they look for one of these patterns to verify the lab requirement was met:
If your transcript shows a 3-credit microbiology course with no separate lab, no “with lab” notation, and no integrated lab in the course description, most programs will require you to retake the course or supplement it with a separate lab. Verify the course numbering and credit structure before enrolling — not after.
Are virtual labs accepted?
Yes, at virtually every CODA-accredited program — provided the lab credit appears on the transcript and the institution issuing the credit is regionally accredited. Virtual lab platforms like Labster, McGraw-Hill Connect Virtual Labs, and HHMI BioInteractive simulations have become widely accepted since the 2020–2022 pandemic-era policy changes that explicitly approved online lab coursework. The shift has been particularly strong in microbiology, where virtual labs can simulate gram staining, bacterial culture, and antibiotic sensitivity testing safely and accurately, often with better outcomes than rushed in-person labs.
The PrereqCourses microbiology course — BIO 210 Microbiology with Lab — uses accepted virtual lab platforms, and the lab credit appears explicitly on the transcript issued by Upper Iowa University. CODA programs that accept regionally accredited prerequisite coursework accept this format.
Specific dental hygiene programs structure their microbiology requirements with meaningful variation in grade thresholds, recency rules, and course numbering. Here’s how three representative programs handle it:
University of Maryland — 4 credits, 7-year recency, C minimum
The University of Maryland Dental Hygiene Bachelor of Science program requires Microbiology with Lab (4 credits) as one of four required science prerequisites totaling at minimum 16 credits. All science courses must be completed within 7 years of application, and all must earn a grade of C or higher — no lower grades accepted, no retake-and-replace policy. Maryland’s policy is representative of the rigorous bachelor’s-level CODA programs: lab required, regional accreditation required, recent coursework required.
CUNY City Tech — 5-year recency, integrated with prerequisite GPA
The CUNY City Tech Dental Hygiene program requires microbiology as a preclinical science course alongside A&P I, A&P II, and Chemistry. All four must be completed within 5 years of acceptance into the clinical program — a strict recency rule that affects many applicants. City Tech evaluates applicants based on prerequisite GPA calculated from these four science courses, making the microbiology grade disproportionately influential in admissions outcomes.
Northern Virginia Community College — B grade required in microbiology specifically
The Northern Virginia Community College Dental Hygiene program requires Microbiology for Health Sciences (BIO 150) with a grade of B or higher specifically — a stricter standard than the C floor most programs accept. This policy reflects how heavily the program leans on microbiology content during the clinical curriculum: students who haven’t mastered the prerequisite material struggle in the program’s oral microbiology and infection control coursework. The recency rule at NVCC is more generous than most (10 years), but the grade requirement is non-negotiable.
The takeaway: microbiology grade matters disproportionately
Across most CODA programs, the microbiology grade carries weight beyond what the credit count would suggest. Admissions committees know that students who do well in microbiology tend to do well in the dental microbiology and infection control content during the program, and students who struggled in microbiology often struggle clinically. A B+ or A in microbiology can offset a weaker grade in another prerequisite; a C in microbiology rarely improves an otherwise strong application.
Once you know microbiology is required, the next decision is where to take it. The choice affects your timeline, cost, transferability, and ultimately your admission chances. Five criteria matter:
1. Regional accreditation of the issuing institution
This is the single most important criterion. CODA-accredited dental hygiene programs almost universally require prerequisite coursework from regionally accredited U.S. institutions. Nationally accredited institutions, vocational schools, foreign universities, and unaccredited online providers will not satisfy the requirement, even if the course content is identical to a regionally accredited course.
The seven recognized regional accreditors are HLC (Higher Learning Commission), MSCHE (Middle States), NECHE (New England), NWCCU (Northwest), SACSCOC (Southern), WSCUC (Western Senior), and ACCJC (Western Junior). Coursework from any institution accredited by one of these seven bodies will be accepted at virtually every CODA-accredited dental hygiene program in the country.
2. Lab component on the transcript
As covered in detail above, the lab credit must appear on the transcript — either as part of an integrated 4-credit “with lab” course or as a separate 1-credit lab course paired with a 3-credit lecture. Verify this before enrolling, not after.
3. Course content focus
Microbiology courses come in flavors. “General Microbiology” for biology majors covers more environmental and evolutionary microbiology and less pathogen-focused content. “Microbiology for Health Sciences” or “Medical Microbiology” emphasizes pathogenic microorganisms and infection control — much more relevant to dental hygiene practice. Both will satisfy the CODA program prerequisite, but the health-sciences-focused version will prepare you better for the dental microbiology content during the program itself.
4. Pacing flexibility
If you’re working full-time, raising children, or balancing other prerequisites simultaneously, fixed-semester pacing at a community college or university extension can be unworkable. Self-paced online microbiology courses let you work through the content in 8 weeks or 6 months depending on your schedule, and let you accelerate if you’re trying to apply by an upcoming deadline.
5. Cost
Microbiology costs vary dramatically by provider:
| Provider type | Typical cost | Notes |
|---|---|---|
| In-state community college | $600–$1,200 | Subsidized; fixed semester pacing; in-person lab |
| Out-of-state community college | $1,800–$3,500 | 2–3x in-state pricing; same scheduling constraints |
| Four-year university extension | $1,500–$3,000 | Often requires admission to institution; recognized name |
| Dedicated online prerequisite provider | $650–$900 | Self-paced; regional accreditation through partner; virtual lab |
Note that price is not a reliable signal of quality or transferability. A $700 microbiology course from a regionally accredited online provider transfers identically to a $2,800 microbiology course from a four-year university extension. The CODA program admissions committee evaluates the regional accreditation, the credits, the lab credit, and the grade — not what you paid for the course.
Microbiology is one of the prerequisites most affected by the science recency rule, and for good reason: microbiology has changed faster in the past decade than almost any other prerequisite biology course. The microbiome content taught in a 2014 microbiology course bears little resemblance to current understanding. CRISPR, modern molecular identification techniques, the explosion of antibiotic resistance, the recognition of the oral microbiome as a complex ecosystem rather than a collection of pathogens — all of this has reshaped microbiology curricula in ways that older coursework simply cannot reflect.
The result: most CODA-accredited programs require microbiology completed within 5–7 years of application. Some programs allow 10 years; a few have no recency rule at all. But the median policy is 5 years, and applicants with older microbiology coursework should plan to retake regardless of their original grade.
| Career changer reality check on microbiology recencyIf you took microbiology more than 5–7 years ago, you almost certainly need to retake it for most CODA dental hygiene programs. This affects a huge number of dental hygiene applicants — career changers from non-science fields whose original microbiology coursework is 8, 10, or 15 years old, and even some current healthcare workers (medical assistants, dental assistants, EMTs) whose microbiology coursework predates the modern microbiome understanding.Retaking microbiology through an online provider is fast and affordable. A self-paced 4-credit microbiology course can be completed in 8–16 weeks for under $700, and the new transcript completely resets the recency clock. You also have the chance to earn a stronger grade than you may have earned years ago — and that updated grade may meaningfully improve your admission odds. |
To make the abstract concrete: here’s how the prerequisite microbiology content shows up in the daily work of a practicing dental hygienist.
Scaling and root planing as biofilm disruption
The fundamental procedure of dental hygiene practice is, microbiologically, the disruption of bacterial biofilm. Subgingival biofilm composed of P. gingivalis, T. forsythia, T. denticola, and Filifactor alocis cannot be addressed with antibiotics alone — the biofilm structure protects the bacteria from systemic antimicrobials. Mechanical disruption with hand instruments and ultrasonic scalers is the only effective treatment. The prerequisite microbiology course covers biofilm structure and antimicrobial resistance in biofilms; the program builds on this with specific subgingival pathogen identification and clinical treatment protocols.
Caries risk assessment
Modern caries risk assessment is increasingly microbiological. Streptococcus mutans levels, salivary buffering capacity, and lactobacilli counts inform individualized prevention plans. Patients with high S. mutans colonization receive targeted antimicrobial mouthrinses, xylitol gum recommendations, and sometimes silver diamine fluoride treatment. Without prerequisite microbiology, the rationale behind these clinical protocols is opaque.
Aerosol management during ultrasonic scaling
Ultrasonic scalers generate dental aerosols containing oral bacteria, viral particles (including SARS-CoV-2 during the COVID-19 pandemic), and saliva droplets. Hygienists must understand particle sizes, droplet vs. aerosol transmission, and the engineering controls (high-volume evacuation, air filtration) that mitigate transmission risk. The 2020–2022 dental practice changes around aerosol-generating procedures relied on exactly the microbiology prerequisite content — droplet dynamics, viral viability in aerosols, transmission risk modeling — that students learn in the microbiology course.
Antibiotic prophylaxis decision-making
Some patients require antibiotic prophylaxis before invasive dental procedures to prevent bacterial endocarditis. Current AHA guidelines have narrowed the indications considerably from earlier protocols, reflecting the microbiological evidence on transient bacteremia, biofilm formation on prosthetic heart valves, and the risks of antibiotic overuse. Hygienists need to understand Streptococcus viridans bacteremia, the rationale for amoxicillin prophylaxis, and the alternative protocols for penicillin-allergic patients. All of this builds on prerequisite microbiology content.
Recognizing oral candidiasis and herpetic lesions
Hygienists are often the first healthcare providers to identify oral fungal infections (denture stomatitis, angular cheilitis, oropharyngeal candidiasis) and viral infections (primary herpetic gingivostomatitis, recurrent herpes labialis). Recognizing these conditions requires understanding Candida albicans growth conditions, the herpes simplex virus latency-reactivation cycle, and the systemic conditions that predispose patients to oral fungal overgrowth (diabetes, immunosuppression, recent antibiotic use). Without prerequisite microbiology, this recognition skill cannot be taught efficiently.
Pathway 1: Community college (in-person)
Cost: $600–$1,200 in-state, $1,800–$3,500 out-of-state. Timeline: one full semester (16 weeks) at semester pace; sometimes available in 8-week summer formats. Pros: in-person lab, established academic infrastructure, often subsidized by state residency. Cons: rigid scheduling makes balancing with work or other prerequisites difficult; out-of-state pricing is prohibitive; campus-based labs require physical attendance.
Pathway 2: Four-year university extension (online or hybrid)
Cost: $1,500–$3,000. Timeline: one semester. Pros: regional accreditation, recognized institution names, sometimes hybrid online/in-person options. Cons: significantly more expensive than community colleges or dedicated online providers; many require formal admission to the institution before allowing prerequisite enrollment; pacing fixed by academic calendar.
Pathway 3: Dedicated online prerequisite provider
Cost: $650–$900. Timeline: 8–16 weeks at full pace; up to 6 months for slower pacing. Pros: lowest-cost option, fully self-paced, designed specifically for prerequisite completion, regional accreditation through partner universities, virtual lab on transcript. Cons: requires self-discipline; not all providers are regionally accredited (verify before enrolling).
PrereqCourses.com falls into the third category. BIO 210 Microbiology with Lab is a 4-credit, fully online, self-paced microbiology course with virtual lab activities, accredited through Upper Iowa University — a regionally accredited institution accredited by the Higher Learning Commission. The course satisfies the microbiology prerequisite at every CODA-accredited dental hygiene program that accepts regionally accredited prerequisite coursework.
Can I take general microbiology, or does it have to be “Microbiology for Health Sciences”?
Either is acceptable at virtually every CODA program. The course title doesn’t matter — what matters is the credit count (3–4 credits, plus lab), the regional accreditation of the issuing institution, and the lab component on the transcript. A 4-credit “General Microbiology with Lab” course satisfies the prerequisite identically to a 4-credit “Microbiology for Health Sciences with Lab” course.
Do I need to take microbiology before A&P, or can they overlap?
Most programs do not require a specific sequence between A&P and microbiology — they can be taken in either order, or simultaneously. Some institutions require A&P I as a prerequisite for their microbiology course (because microbiology assumes some understanding of the immune system, which is covered in A&P II), but this is institution-specific, not CODA-program-specific. The dental hygiene admissions committee doesn’t care about the order; they care that both are complete and recent.
What if I took microbiology as part of a nursing program — does that count?
Yes, in virtually all cases. “Microbiology for Nursing” or “Microbiology for Allied Health” courses count identically to general microbiology, provided they’re 3–4 credits with a lab component and from a regionally accredited institution. The dental hygiene admissions committee is verifying that you’ve completed accredited microbiology coursework with a lab — not that the course was specifically branded for dental hygiene applicants.
Is virology or immunology a substitute for microbiology?
No. Virology and immunology are typically upper-division courses that cover narrower content than general microbiology. CODA programs require the broad foundational content of microbiology — bacterial structure, sterilization, infection control, pathogen identification — which is not adequately covered in a virology or immunology course. These courses can be excellent supplemental coursework but do not substitute for the microbiology prerequisite.
Can I CLEP or test out of microbiology?
No. CLEP exams are not offered for microbiology, and CODA programs require coursework on a transcript with a lab component — neither of which a standardized exam provides. Microbiology must be completed as actual coursework at a regionally accredited institution.
How long does the microbiology prerequisite take to complete online?
With self-paced online microbiology, motivated students complete the course in 8–16 weeks of focused study — about 10–15 hours per week. The lab activities, which are completed virtually, add another 2–4 hours per week. Students balancing work and other prerequisites can take up to 6 months without losing momentum, while students racing toward an upcoming application deadline can complete it in 6–8 weeks at an intensive pace.
Microbiology is the prerequisite biology course most directly tied to the daily work of dental hygiene practice. It’s required by virtually every CODA-accredited program in the country. It must include a lab component. It should be recent. And it should be completed at a regionally accredited institution — because that’s the standard CODA-accredited programs use to evaluate transferability.
PrereqCourses.com offers the microbiology prerequisite in a format designed specifically for dental hygiene applicants:
Whether you’re starting from scratch as a career changer, refreshing expired microbiology coursework after a 5-year-plus gap, or strengthening a previously weak grade, the path is the same: complete a 4-credit microbiology course with a lab component at a regionally accredited institution, earn a strong grade (B+ or better for competitive programs), and submit the transcript with your dental hygiene application.
Visit PrereqCourses.com to enroll in BIO 210 Microbiology with Lab and complete the most dental-relevant prerequisite in your dental hygiene application stack.
