22 Asepsis During Imaging Practice Questions & Answers

1. 1. An assistant is sorting the items used for a full-mouth radiographic series into the Spaulding categories used by the CDC. Where does an intraoral image receptor that is placed in the patient's mouth belong, and what does that category require?

   • A.Semicritical, because it contacts mucous membranes; heat-sterilize it if heat-tolerant, otherwise barrier and disinfect it.✓ Answer
   • B.Noncritical, because it is an electronic device; a moisture-impervious barrier by itself protects the following patient.
   • C.Noncritical, because it touches only intact skin and mucosa; cleaning with detergent and water between patients is enough.
   • D.Critical, because it contacts saliva that may carry blood; it must be heat-sterilized in a pouch before every use.

   Spaulding categories are assigned by what the item contacts, not by what the item costs or whether it is electronic. Any receptor placed in the mouth contacts mucous membranes, which makes it semicritical: heat-sterilize it when the device tolerates heat, and when it does not, use an FDA-cleared barrier plus cleaning and disinfection.

   Source: CDC, Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003) — Spaulding classification of patient-care items; CDC Summary of Infection Prevention Practices in Dental Settings (2016)Report a problem with this question

2. 2. The CDC's list of noncritical patient-care items in dentistry expressly includes radiograph heads. How must the tubehead of the dental x-ray unit be handled between two patients?

   • A.It is treated as a housekeeping surface and cleaned with detergent and water at the end of each clinic day.
   • B.It is sterilized on the same cycle as the receptor holders because it is positioned against the patient's cheek.
   • C.It is wiped with an alcohol pad only when the operator's gloves visibly touched it during the exposure.
   • D.It is covered with a barrier that is changed for each patient, or cleaned and disinfected when left uncovered.✓ Answer

   A noncritical item contacts intact skin only, so it does not require sterilization; it requires a barrier changed between patients, or cleaning followed by disinfection when no barrier is used. The tubehead is irregular and hard to clean, which is why a barrier is generally the practical choice.

   Source: CDC Summary of Infection Prevention Practices in Dental Settings (2016) — noncritical items and environmental surfaces; CDC Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003)Report a problem with this question

3. 3. A wired CMOS sensor is used for a bitewing series. The manufacturer states that it cannot be autoclaved and cannot be immersed. How should it be reprocessed between patients?

   • A.Skip the barrier and instead submerge the sensor in a high-level disinfectant solution for the labeled contact time.
   • B.Skip the barrier and instead wipe the sensor with a low-level product that claims activity against HIV and HBV only.
   • C.Use an FDA-cleared barrier for the exposures, then clean the sensor and disinfect it with a tuberculocidal product.✓ Answer
   • D.Use an FDA-cleared barrier for the exposures, and treat the sensor as clean once the intact barrier has been removed.

   Barriers leak and tear more often than staff realize, so the CDC directs that a heat-labile semicritical device receive both an FDA-cleared barrier during use and cleaning followed by intermediate-level disinfection afterward. Intermediate level is identified on the label by a tuberculocidal claim.

   Source: CDC Summary of Infection Prevention Practices in Dental Settings (2016) — digital radiography sensors; CDC Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003)Report a problem with this question

4. 4. A photostimulable phosphor plate is contaminated with saliva during a periapical series. How should that plate be protected during use and handled afterward?

   • A.Submerge it in an intermediate-level disinfectant for the labeled contact time and air-dry it before the next patient.
   • B.Enclose it in a barrier envelope for each use, then run it through a steam cycle at the close of the clinic session.
   • C.Scrub it with gauze and a disinfectant wipe after each exposure, which also clears the residual image from the plate.
   • D.Enclose it in a barrier envelope for each use, then clean the plate itself only as the manufacturer's instructions allow.✓ Answer

   A phosphor plate is heat-labile and its active surface is damaged by abrasion and by liquids, and damage shows up as artifacts on later images. It is therefore protected by a barrier envelope for every exposure, and the plate itself is reprocessed only in the way the device's instructions for use permit.

   Source: CDC Summary of Infection Prevention Practices in Dental Settings (2016) — semicritical devices that cannot be heat-sterilized; Iannucci & Howerton, Dental Radiography: Principles and Techniques — infection control in digital imagingReport a problem with this question

5. 5. The office stocks autoclavable beam alignment devices with bite blocks. A full-mouth series has just been completed with two of them. How should those devices be handled?

   • A.Rinse them under running water at the operatory sink and store them dry until the first patient the next morning.
   • B.Transport them in a covered container, then clean, package, and heat-sterilize them before they are used again.✓ Answer
   • C.Transport them in a covered container, then wipe them with a tuberculocidal disinfectant and return them to the tray.
   • D.Soak them in a chemical sterilant overnight, since the bite block contacts only saliva and never contacts blood.

   Holders and bite blocks enter the mouth, so they are semicritical, and a semicritical item that tolerates heat must be heat-sterilized rather than merely disinfected. Contaminated items are carried to the processing area in a covered, leakproof container so that the trip does not spread contamination.

   Source: CDC Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003) — semicritical instruments and transport of contaminated items; Iannucci & Howerton, Dental Radiography: Principles and TechniquesReport a problem with this question

6. 6. At the end of an imaging appointment, the used barrier envelopes and the disposable bite tabs from the bitewing series are on the tray. How should those items be handled?

   • A.They are wiped with a tuberculocidal disinfectant and returned to the supply drawer for the next patient of the day.
   • B.They are discarded with the other single-use waste, because a single-use device is not reprocessed for anyone else.✓ Answer
   • C.They are placed in the ultrasonic cleaner along with the holders and reused once the cycle and the rinse are done.
   • D.They are rinsed, dried, and stored in a labeled bag so that the same patient can use them at a later appointment.

   A single-use device is designed and cleared for one patient and one procedure, and it cannot be reliably cleaned or validated for reuse afterward. Barrier envelopes, plastic sleeves, and disposable bite tabs therefore go into the waste stream at the end of the appointment.

   Source: CDC Summary of Infection Prevention Practices in Dental Settings (2016) — single-use (disposable) devices; FDA labeling of single-use devicesReport a problem with this question

7. 7. Midway through a full-mouth series the assistant notices that the plastic barrier over the exposure button has torn and that the button underneath was pressed with contaminated gloves. What should be done with that button?

   • A.Spray the button once with disinfectant and wipe it dry at once so that the electronics are not damaged by liquid.
   • B.Wipe the button with an alcohol pad and finish the series, then disinfect the surface after the patient is dismissed.
   • C.Replace the torn barrier with a fresh one, since a surface under a barrier stays uncontaminated during the series.
   • D.Clean the button of debris first, then disinfect it with an EPA-registered tuberculocidal product for its wet time.✓ Answer

   Organic debris such as saliva binds and inactivates disinfectant, so cleaning must always precede disinfection, and the surface has to stay visibly wet for the contact time printed on the product label. A torn barrier means the surface beneath it must be treated as contaminated.

   Source: CDC Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003) — clinical contact surfaces and surface barriers; EPA registration of hospital disinfectants with tuberculocidal claimReport a problem with this question

8. 8. An office is choosing surface barriers for the x-ray control panel, the tubehead, and the chair headrest in the radiography operatory. Which statement about those barriers is correct?

   • A.Barriers are needed on the surfaces an operator touches bare-handed, not on those touched with a gloved hand.
   • B.Barriers must be impervious to moisture, and they are replaced between patients with clean, ungloved hands.✓ Answer
   • C.Barriers may be any clean paper or cloth cover, as long as a fresh one is put in place for each new patient.
   • D.Barriers are changed at midday and again at the end of the day, provided no visible spatter has appeared on them.

   A barrier only works if fluid cannot pass through it, so paper and cloth do not qualify, and it must be replaced for every patient because it is contaminated once used. Fresh barriers are placed after gloves are removed and hand hygiene is done, so the clean cover is not contaminated as it is applied.

   Source: CDC Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003) — surface barriers for clinical contact surfacesReport a problem with this question

9. 9. Before seating a patient for a four-image bitewing series, the assistant must prepare the operatory. Which sequence is correct?

   • A.Place the barriers with gloved hands, remove those gloves, seat the patient, and open the holders after the first image.
   • B.Seat the patient first, put on gloves, and then place the barriers and open the packaged holders on the counter.
   • C.Perform hand hygiene, place the barriers and set out the holders and receptors, seat the patient, then glove.✓ Answer
   • D.Put on gloves, place the barriers and set out the holders and receptors, then seat the patient and begin.

   Everything the operator will need is laid out with clean hands before the appointment begins, because nothing may be opened or retrieved once gloves have touched the patient's mouth. Gloves are the last item donned, immediately before the exposures start.

   Source: CDC Summary of Infection Prevention Practices in Dental Settings (2016) — preparing the treatment area; Iannucci & Howerton, Dental Radiography: Principles and Techniques — infection control before exposureReport a problem with this question

10. 10. The last image of a series has been exposed and the patient has been dismissed. Which breakdown sequence for the radiography operatory is correct?

    • A.Remove the gloves and perform hand hygiene first, then strip the used barriers and collect the holders bare-handed.
    • B.Still gloved, carry the receptors and the holders together to the scanner, then come back to strip off the barriers.
    • C.Still gloved, discard the single-use items and barriers and bag the holders, then remove the gloves and clean the hands.✓ Answer
    • D.Remove the gloves, pull on a fresh pair of exam gloves, and use that pair to clean and disinfect the open surfaces.

    Contaminated items are handled while the hands are still protected, so barriers and disposables are removed and the holders are contained before the gloves come off. Hand hygiene follows glove removal because hands become contaminated during doffing and through unseen glove defects.

    Source: CDC Summary of Infection Prevention Practices in Dental Settings (2016) — environmental infection prevention and hand hygiene; Iannucci & Howerton, Dental Radiography: Principles and TechniquesReport a problem with this question

11. 11. The barriers have been removed and the uncovered counter, chair controls, and extension arm in the radiography operatory must now be cleaned and disinfected. Which hand protection is correct for that task?

    • A.A fresh pair of exam gloves, which are then discarded as soon as the surfaces have all been disinfected.
    • B.Heavy-duty utility gloves, which may then be washed and reused according to the manufacturer's directions.✓ Answer
    • C.Clear plastic overgloves pulled over the treatment gloves, which keeps the disinfectant off the operator's skin.
    • D.The same exam gloves worn for the exposures, since those surfaces are already regarded as contaminated.

    Thin exam gloves are not built for the punctures and the chemical exposure of operatory cleanup, and disinfectants degrade them quickly. Puncture-resistant utility gloves are the designated equipment for surface cleaning and instrument handling, and they are reusable after cleaning.

    Source: CDC Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003) — puncture-resistant utility gloves for cleaning and disinfectionReport a problem with this question

12. 12. The exposed phosphor plates are sitting in a covered container in the operatory and must now be carried to the scanning area. What should the assistant do?

    • A.Remove the gloves, perform hand hygiene, and then carry the covered container with clean, ungloved hands.✓ Answer
    • B.Pass the container to a gloved co-worker so that the operator does not have to leave the imaging operatory at all.
    • C.Pull overgloves over the contaminated treatment gloves and carry the container to the scanning station in those.
    • D.Keep the contaminated treatment gloves on to carry the container, and remove them once at the scanning station.

    Contaminated gloves spread saliva to every door handle, drawer, and keyboard touched along the way, so the trip out of the operatory is made with clean hands. The receptors themselves stay contained, which is what keeps the scanning area clean.

    Source: CDC Summary of Infection Prevention Practices in Dental Settings (2016) — hand hygiene and transport of contaminated items; Iannucci & Howerton, Dental Radiography: Principles and TechniquesReport a problem with this question

13. 13. During a full-mouth series, where should each receptor be placed as it is taken out of the patient's mouth and the next exposure is set up?

    • A.In a disposable cup or a covered container that was set aside for the exposed receptors before the series began.✓ Answer
    • B.On the barrier covering the tubehead, which is then discarded together with the receptors at the end of the series.
    • C.In the operator's free hand or uniform pocket until the entire series of exposures has finally been completed.
    • D.On the uncovered counter next to the control panel, arranged in order by the region that has just been exposed.

    Every exposed receptor is wet with saliva, so it must be contained rather than laid on a clinical contact surface that would then have to be cleaned and disinfected. A cup or covered container also keeps the images in order and prevents a receptor from being dropped or lost.

    Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — handling exposed receptors; CDC Summary of Infection Prevention Practices in Dental Settings (2016)Report a problem with this question

14. 14. In the middle of a series the assistant must change a setting on the imaging computer, whose keyboard carries no barrier. What is the correct way to do that?

    • A.Wipe the treatment gloves with disinfectant, change the setting, and continue the series in those gloves.
    • B.Change the setting with the treatment gloves on, and then disinfect the keyboard after the patient has left.
    • C.Place overgloves over the treatment gloves, change the setting, then remove the overgloves and go on.✓ Answer
    • D.Remove one treatment glove, change the setting bare-handed, and pull that same glove back on afterward.

    Overgloves exist precisely so that a contaminated hand can touch a clean item without transferring saliva to it, and they are removed the moment the clean task is finished. Disposable treatment gloves are never washed or disinfected for continued use, because the chemicals degrade the glove material.

    Source: CDC Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003) — overgloves and prohibition on washing patient examination glovesReport a problem with this question

15. 15. After removing her gloves at the end of an imaging appointment, the assistant sees that saliva leaked through a defect and her hands are visibly wet with it. What hand hygiene is required?

    • A.Wash the hands with soap and running water, because visibly soiled hands must be washed rather than rubbed.✓ Answer
    • B.Apply the alcohol rub twice, because the doubled volume compensates for the visible saliva on the skin.
    • C.Rinse the hands with water and re-glove, because the next pair of gloves will contain any residual soil.
    • D.Apply an alcohol-based hand rub, because it kills more organisms than plain soap and running water do.

    Alcohol rubs are inactivated by organic material and cannot physically remove soil, so washing with soap and running water is required whenever hands are visibly soiled or contaminated with blood or saliva. The mechanical action of washing carries the material off the skin.

    Source: CDC Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003) — hand hygiene indications and methodsReport a problem with this question

16. 16. Which hand hygiene practice is correct across a day of radiographic appointments?

    • A.Hands are cleaned once at the start of the session and again when the final patient of the day is dismissed.
    • B.Hands are cleaned after glove removal only, because a fresh pair of gloves is already sterile when opened.
    • C.Hands are cleaned before gloving and again after glove removal, and dried completely before gloves go on.✓ Answer
    • D.Hands are cleaned before gloving only, because intact gloves keep the hands clean throughout the series.

    Gloves are not a substitute for hand hygiene: they carry microscopic perforations, and the hands are contaminated during removal. Hands must also be dry before gloving, because moisture trapped inside the glove promotes microbial growth and skin irritation.

    Source: CDC Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003) — hand hygiene and glove useReport a problem with this question

17. 17. An assistant is about to expose an intraoral series and will wear protective clothing, a mask, eyewear with side shields, and gloves. What is the correct order for putting them on?

    • A.Eyewear, then mask, then gloves, and then protective clothing.
    • B.Mask, then eyewear, then protective clothing, and then gloves.
    • C.Gloves, then protective clothing, then mask, and then eyewear.
    • D.Protective clothing, then mask, then eyewear, then gloves.✓ Answer

    Personal protective equipment is donned from the body outward, so the gown goes on first and the gloves go on last, pulled over the cuffs of the sleeves. Gloves are last because anything touched after gloving would contaminate them before the patient is even seated.

    Source: CDC Summary of Infection Prevention Practices in Dental Settings (2016) — sequence for donning personal protective equipmentReport a problem with this question

18. 18. The series is finished and the assistant is still wearing protective clothing, a mask, eyewear, and gloves. What is the correct order for taking that equipment off?

    • A.Eyewear, then gloves, then mask, and then protective clothing, followed by hand hygiene.
    • B.Gloves, then protective clothing, then eyewear, then mask, followed by hand hygiene.✓ Answer
    • C.Mask, then eyewear, then protective clothing, and then gloves, followed by hand hygiene.
    • D.Protective clothing, then gloves, then mask, and then eyewear, followed by hand hygiene.

    Doffing runs from the most contaminated item to the least, so the gloves come off first and the mask, which is touched only by its ties or ear loops, comes off last. Hand hygiene follows immediately, because the hands inevitably contact contaminated surfaces during removal.

    Source: CDC Summary of Infection Prevention Practices in Dental Settings (2016) — sequence for removing personal protective equipmentReport a problem with this question

19. 19. Between two radiographic appointments, how should the assistant's mask and protective eyewear be handled?

    • A.The mask is changed for each patient, and the eyewear is discarded with the gloves as a single-use item.
    • B.The mask is changed for each patient, and the eyewear is cleaned and then disinfected between patients.✓ Answer
    • C.The mask is changed when visibly spattered, and the eyewear is rinsed with water at the end of the day.
    • D.The mask is worn under the chin between patients, and the eyewear is left uncovered on the counter.

    A mask becomes contaminated on both surfaces as it filters, so it is changed for every patient and is never pulled down and reused; wearing it under the chin transfers organisms to the neck and back to the face. Reusable eyewear is cleaned of debris and then disinfected before the next patient.

    Source: CDC Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003) — masks, protective eyewear and face shieldsReport a problem with this question

20. 20. At the scanning station the assistant is holding exposed phosphor plates that are still inside their contaminated barrier envelopes. Which handling sequence is correct?

    • A.Open each envelope so the plate drops onto a clean surface, then handle the plate with clean hands or fresh gloves.✓ Answer
    • B.Wipe each envelope with a disinfectant, then scan the plate while it stays sealed inside its own envelope.
    • C.Peel each envelope open and slide the plate back into that same envelope once it has been scanned and erased.
    • D.Pull each plate out of its envelope by the edges, using the same gloves that were worn for the exposures.

    The outside of the envelope is contaminated and the plate inside is not, so the plate must leave the envelope without the hands or the plate touching that outer surface. Dropping it onto a clean surface preserves that separation, and the plate then goes into a new envelope for the next patient.

    Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — handling contaminated phosphor plate barrier envelopes; CDC Summary of Infection Prevention Practices in Dental Settings (2016)Report a problem with this question

21. 21. During a series with a wired sensor, the assistant repeatedly handles the cable while repositioning the sensor in the patient's mouth. How should the cable be managed?

    • A.The cable is covered by the barrier where it is handled, and is cleaned and disinfected with the sensor.✓ Answer
    • B.The cable is wiped with alcohol at the end of the day, which is enough for a surface touched by gloved hands.
    • C.The cable is wrapped in a paper towel during the series, and the towel is then discarded with the used barriers.
    • D.The cable needs no covering at all, because it never enters the mouth and does not contact mucous membranes.

    The cable is touched by the same contaminated gloves that positioned the sensor, and saliva runs down it out of the mouth, so it becomes contaminated even though it stays outside the mucosa. It is therefore barriered along the handled length and reprocessed with the sensor between patients.

    Source: CDC Summary of Infection Prevention Practices in Dental Settings (2016) — digital radiography sensors and associated components; Iannucci & Howerton, Dental Radiography: Principles and TechniquesReport a problem with this question

22. 22. How should the lead apron and thyroid collar be cleaned and stored between patients in the radiography operatory?

    • A.Run them through a steam sterilization cycle each week and hang them to dry fully between the patients.
    • B.Cover them with a plastic barrier and store them folded on the counter beside the x-ray unit until needed.
    • C.Fold them in quarters and store them in a closed drawer so that the lead is protected from dust and light.
    • D.Wipe them with a surface disinfectant and hang or drape them so that the lead inside does not crack.✓ Answer

    The apron contacts only intact skin and clothing, which makes it a noncritical item that is cleaned and disinfected on its surface rather than heat-processed; heat would destroy the vinyl cover. Folding creases the lead and eventually cracks it, leaving gaps that no longer attenuate the beam.

    Source: CDC Guidelines for Infection Control in Dental Health-Care Settings (MMWR 2003) — noncritical items and environmental surfaces; Iannucci & Howerton, Dental Radiography: Principles and Techniques — care of lead apronsReport a problem with this question

Practice questions only — not real exam items, and not affiliated with or endorsed by the Dental Assisting National Board. Questions are written to the domains published in DANB's current RHS and ICE exam outlines, and cover digital radiography only, matching DANB's statement that film-based concepts are no longer tested. This bank does not cover the chairside assisting or dental anatomy component exams. What a dental assistant is legally allowed to do — including who may expose radiographs and what training a state requires first — is set by each state's dental board and is deliberately out of scope here. Exam format, eligibility, and scoring are set by DANB and change from time to time; confirm the current requirements with DANB and your state board before you register. Official DANB exam outlines →