DANB Dental Assisting (RHS + ICE) Practice Test

Câu hỏi luyện tập mẫu

Một vài câu hỏi thực tế từ ngân hàng miễn phí này, kèm giải thích đầy đủ. Dùng công cụ luyện tập ở trên cho toàn bộ.

1. 1. Radiation Health & Safety

   A dental assistant is asked to explain the ALARA concept to a new hire. Which statement best describes ALARA?

   • a.Exposure may be increased if that produces a sharper image
   • b.Only the patient's exposure must be minimized, not the x-ray operator's
   • c.Every reasonable step should be taken to keep exposure As Low As Reasonably Achievable
   • d.Radiation exposure is safe as long as it stays under the annual legal limit

   Đáp án: c

   Giải thích: ALARA stands for As Low As Reasonably Achievable, meaning exposure to patients and staff should be reduced to the lowest practical level even when legal limits are not exceeded. Staying under the annual legal limit is a minimum requirement rather than the goal, so calling any exposure safe simply because it is under that limit is wrong. ALARA protects both patients and operators, and image quality is achieved through correct technique rather than extra radiation.

   Nguồn: NCRP Report No. 145: Radiation Protection in Dentistry

2. 2. Radiographic Technique

   Which description matches the paralleling technique for intraoral radiography?

   • a.The receptor is placed parallel to the long axis of the tooth and the central ray is directed perpendicular to both
   • b.The receptor is placed outside the cheek and the beam passes through the face from the far side
   • c.The receptor is held in place by the patient's finger at a 45-degree angle
   • d.The receptor rests against the tooth and the beam is aimed at an imaginary bisector

   Đáp án: a

   Giải thích: In the paralleling technique a holding device positions the receptor parallel to the long axis of the tooth, and the central ray is directed perpendicular to both, which minimizes dimensional distortion. Aiming at an imaginary bisector describes the bisecting technique. Finger holding is discouraged because it causes movement and unnecessary exposure, and placing the receptor outside the cheek describes extraoral imaging.

3. 3. Infection Control

   How should an instrument processing area be laid out?

   • a.In a single direction from the contaminated receiving and cleaning area, to preparation and packaging, to sterilization, to clean storage
   • b.Instruments should be packaged first so they can be cleaned inside the sealed pouch during the cycle
   • c.Clean and contaminated items may share a single counter as long as it is wiped down between each patient
   • d.Sterile storage should sit closest to the contaminated sink so that packages are within easy reach

   Đáp án: a

   Giải thích: The processing area must flow in one direction from dirty to clean, moving from receiving and cleaning through preparation and packaging to sterilization and finally to clean storage, so processed items are never recontaminated. Sharing a counter and placing sterile storage next to the dirty sink both invite cross-contamination. Instruments must always be cleaned before packaging, because debris shields microorganisms from the sterilant.

   Nguồn: CDC Guidelines for Infection Control in Dental Health-Care Settings

4. 4. Patient Safety & Law

   A patient with a history of angina develops crushing chest pain in the chair. Besides stopping treatment and activating emergency medical services, which drug from the office emergency kit is typically indicated?

   • a.Nitroglycerin, administered sublingually
   • b.Oral glucose gel placed in the buccal vestibule
   • c.Diphenhydramine, given by intramuscular injection
   • d.Albuterol delivered by a metered-dose inhaler

   Đáp án: a

   Giải thích: Sublingual nitroglycerin is the standard emergency drug for angina because it dilates coronary vessels and relieves ischemic chest pain. Diphenhydramine is used for allergic reactions, and albuterol is for bronchospasm in asthma. Glucose gel treats hypoglycemia and would do nothing for cardiac chest pain, so recognizing the correct emergency category is essential.

5. 5. Radiation Health & Safety

   A patient asks how the radiation from a set of bitewings compares with the radiation she encounters in everyday life. Which response is accurate?

   • a.A set of bitewings delivers about as much radiation as a whole year of natural background
   • b.Background radiation comes only from man-made sources such as x-ray machines
   • c.It adds a small amount to the natural background everyone already receives
   • d.Dental x-rays are the largest source of radiation for most people

   Đáp án: c

   Giải thích: Everyone is continuously exposed to natural background radiation from radon, cosmic rays, the soil and naturally occurring radionuclides inside the body, and a bitewing survey taken with modern receptors and good collimation adds only a small increment on top of that. Equating a few bitewings with a whole year of background overstates the comparison by a wide margin, and it is the most tempting wrong answer because patients routinely overestimate dental dose. Background is largely natural rather than man-made - indoor radon is the largest natural contributor across much of the United States - and telling a patient that dental imaging is her largest source of radiation is not accurate.

6. 6. Infection Control

   Placing a rubber dam and using high-volume evacuation cuts down the spray and aerosol that leave the patient's mouth during a restorative procedure. Which link in the chain of infection does this act on most directly?

   • a.The portal of entry into the host
   • b.The susceptible host
   • c.The reservoir of microorganisms
   • d.The mode of transmission

   Đáp án: d

   Giải thích: Spray and aerosol are the vehicle that carries oral microorganisms to the team, to surfaces and on to the next patient, so cutting them down attacks the way organisms travel. The portal of entry is the tempting alternative, because the operator's eyes, nose and mouth are how organisms get in, but that link is guarded by the mask and eyewear the operator wears rather than by controlling what leaves the mouth. The patient's own oral flora, the reservoir, is unchanged, and nothing about a rubber dam makes the team less susceptible.

7. 7. Infection Control

   In the in-office laboratory a prosthesis is polished on a lathe. Which practice controls cross-contamination during that step?

   • a.The same pumice pan is kept in use all day, and a disinfectant is stirred into the slurry at closing time to decontaminate it
   • b.The lathe is barriered, so the pumice underneath can be reused
   • c.A fresh mix of pumice and a sterilized or single-use rag wheel are used for each case, and the pan is cleaned afterwards
   • d.One rag wheel is used all day and rinsed under running water between cases

   Đáp án: c

   Giải thích: Pumice slurry and rag wheels are classic cross-contamination reservoirs, because material from one case stays in the pan and in the wheel fibers; the control is a fresh mix and a sterilized or disposable wheel per case, with the pan cleaned and the lathe disinfected afterwards. Adding disinfectant to a shared pan at the end of the day is tempting because it sounds like decontamination, but every case that day was polished in the contaminated slurry before that step. Rinsing a wheel under water does not disinfect it, and a barrier on the lathe housing does nothing for the slurry itself.

8. 8. Radiographic Technique

   Bitewings are taken with an adhesive tab instead of a holder that carries an external aiming ring. Which errors become more likely?

   • a.Overlap and cone cuts
   • b.Elongation of the roots
   • c.Reversed-receptor herringbone artifacts
   • d.Foreshortening of the roots

   Đáp án: a

   Giải thích: With a tab, nothing outside the mouth shows where the receptor is lying, so both the horizontal direction of the beam and the coverage of the receptor are estimated from the shape of the arch — which is exactly why overlapping contacts and cone cutting are the classic tab errors and why an aiming ring reduces them. Elongation and foreshortening come from vertical-angulation faults in periapical technique and are not what a tab produces on a bitewing, where the receptor is held upright between the arches and the vertical angle is fixed. The herringbone pattern appears when a film packet is placed backwards, and the tab is attached to a defined side of the receptor, so reversal is not the risk a tab introduces.

9. 9. Radiographic Technique

   Two periapicals of the same tooth differ in size, the tooth appearing larger on one of them. Which geometric change magnifies the image?

   • a.The exposure time was increased, which enlarges the recorded outline of the tooth
   • b.A greater tooth-to-receptor distance, or a shorter source-to-tooth distance
   • c.A longer position-indicating device was used
   • d.A higher kilovoltage was selected

   Đáp án: b

   Giải thích: Magnification is pure geometry: the further the tooth sits from the receptor, or the closer the source sits to the tooth, the more the beam diverges before it reaches the receptor and the larger and less sharp the image becomes. A longer position-indicating device is the trap, because it does change magnification, but it increases the source-to-object distance and therefore reduces it. Exposure time and kilovoltage change how dark and how contrasty the image is, not how big the tooth appears.

10. 10. Patient Safety & Law

    A patient asks the office to hand over 'my x-rays' so she can take them to a specialist herself. In most states, what is correct?

    • a.The patient owns the images because she paid for them, so the originals are handed over
    • b.The practice owns the records, and the patient is entitled to copies
    • c.The images may be released only to another dentist
    • d.Nothing may be released without a court order

    Đáp án: b

    Giải thích: In most states the dental record, including the radiographs, is the property of the dentist or the practice, while the information it contains belongs to the patient, who has a right of access; the office therefore supplies copies or duplicates — a digital export, printed images or duplicate films — and keeps the originals in the chart. Paying for treatment buys the service and the information, not the original document, which is the most tempting error here. Releasing to another dentist only would deny the patient's own right of access, and a routine authorised release needs no court order.